diff --git a/src/main/java/io/reactivex/rxjava3/core/Completable.java b/src/main/java/io/reactivex/rxjava3/core/Completable.java
index 96eb10c447..2f424fd405 100644
--- a/src/main/java/io/reactivex/rxjava3/core/Completable.java
+++ b/src/main/java/io/reactivex/rxjava3/core/Completable.java
@@ -630,7 +630,7 @@ public static Completable fromFuture(@NonNull Future<?> future) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Completable fromMaybe(@NonNull MaybeSource<T> maybe) {
+    public static <@NonNull T> Completable fromMaybe(@NonNull MaybeSource<T> maybe) {
         Objects.requireNonNull(maybe, "maybe is null");
         return RxJavaPlugins.onAssembly(new MaybeIgnoreElementCompletable<>(maybe));
     }
@@ -686,7 +686,7 @@ public static Completable fromRunnable(@NonNull Runnable run) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Completable fromObservable(@NonNull ObservableSource<T> observable) {
+    public static <@NonNull T> Completable fromObservable(@NonNull ObservableSource<T> observable) {
         Objects.requireNonNull(observable, "observable is null");
         return RxJavaPlugins.onAssembly(new CompletableFromObservable<>(observable));
     }
@@ -724,7 +724,7 @@ public static <T> Completable fromObservable(@NonNull ObservableSource<T> observ
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Completable fromPublisher(@NonNull Publisher<T> publisher) {
+    public static <@NonNull T> Completable fromPublisher(@NonNull Publisher<T> publisher) {
         Objects.requireNonNull(publisher, "publisher is null");
         return RxJavaPlugins.onAssembly(new CompletableFromPublisher<>(publisher));
     }
@@ -746,7 +746,7 @@ public static <T> Completable fromPublisher(@NonNull Publisher<T> publisher) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Completable fromSingle(@NonNull SingleSource<T> single) {
+    public static <@NonNull T> Completable fromSingle(@NonNull SingleSource<T> single) {
         Objects.requireNonNull(single, "single is null");
         return RxJavaPlugins.onAssembly(new CompletableFromSingle<>(single));
     }
@@ -1225,7 +1225,7 @@ public static Completable switchOnNextDelayError(@NonNull Publisher<@NonNull ? e
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <R> Completable using(@NonNull Supplier<R> resourceSupplier,
+    public static <@NonNull R> Completable using(@NonNull Supplier<R> resourceSupplier,
             @NonNull Function<? super R, ? extends CompletableSource> sourceSupplier,
             @NonNull Consumer<? super R> resourceCleanup) {
         return using(resourceSupplier, sourceSupplier, resourceCleanup, true);
@@ -1261,7 +1261,7 @@ public static <R> Completable using(@NonNull Supplier<R> resourceSupplier,
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <R> Completable using(
+    public static <@NonNull R> Completable using(
             @NonNull Supplier<R> resourceSupplier,
             @NonNull Function<? super R, ? extends CompletableSource> sourceSupplier,
             @NonNull Consumer<? super R> resourceCleanup,
@@ -2194,7 +2194,7 @@ public final Completable lift(@NonNull CompletableOperator onLift) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T> Single<Notification<T>> materialize() {
+    public final <@NonNull T> Single<Notification<T>> materialize() {
         return RxJavaPlugins.onAssembly(new CompletableMaterialize<>(this));
     }
 
@@ -2356,7 +2356,7 @@ public final Completable onErrorResumeWith(@NonNull CompletableSource fallback)
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T> Maybe<T> onErrorReturn(@NonNull Function<? super Throwable, ? extends T> itemSupplier) {
+    public final <@NonNull T> Maybe<T> onErrorReturn(@NonNull Function<? super Throwable, ? extends T> itemSupplier) {
         Objects.requireNonNull(itemSupplier, "itemSupplier is null");
         return RxJavaPlugins.onAssembly(new CompletableOnErrorReturn<>(this, itemSupplier));
     }
@@ -2384,7 +2384,7 @@ public final <T> Maybe<T> onErrorReturn(@NonNull Function<? super Throwable, ? e
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T> Maybe<T> onErrorReturnItem(@NonNull T item) {
+    public final <@NonNull T> Maybe<T> onErrorReturnItem(@NonNull T item) {
         Objects.requireNonNull(item, "item is null");
         return onErrorReturn(Functions.justFunction(item));
     }
@@ -2483,7 +2483,7 @@ public final Completable repeatUntil(@NonNull BooleanSupplier stop) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Completable repeatWhen(@NonNull Function<? super Flowable<Object>, ? extends Publisher<@NonNull ?>> handler) {
+    public final Completable repeatWhen(@NonNull Function<? super Flowable<Object>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         return fromPublisher(toFlowable().repeatWhen(handler));
     }
 
@@ -2655,7 +2655,7 @@ public final Completable retryUntil(@NonNull BooleanSupplier stop) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Completable retryWhen(@NonNull Function<? super Flowable<Throwable>, ? extends Publisher<@NonNull ?>> handler) {
+    public final Completable retryWhen(@NonNull Function<? super Flowable<Throwable>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         return fromPublisher(toFlowable().retryWhen(handler));
     }
 
@@ -2726,7 +2726,7 @@ public final Completable startWith(@NonNull CompletableSource other) {
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public final <T> Flowable<T> startWith(@NonNull SingleSource<T> other) {
+    public final <@NonNull T> Flowable<T> startWith(@NonNull SingleSource<T> other) {
         Objects.requireNonNull(other, "other is null");
         return Flowable.concat(Single.wrap(other).toFlowable(), toFlowable());
     }
@@ -2752,7 +2752,7 @@ public final <T> Flowable<T> startWith(@NonNull SingleSource<T> other) {
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public final <T> Flowable<T> startWith(@NonNull MaybeSource<T> other) {
+    public final <@NonNull T> Flowable<T> startWith(@NonNull MaybeSource<T> other) {
         Objects.requireNonNull(other, "other is null");
         return Flowable.concat(Maybe.wrap(other).toFlowable(), toFlowable());
     }
@@ -2774,7 +2774,7 @@ public final <T> Flowable<T> startWith(@NonNull MaybeSource<T> other) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T> Observable<T> startWith(@NonNull ObservableSource<T> other) {
+    public final <@NonNull T> Observable<T> startWith(@NonNull ObservableSource<T> other) {
         Objects.requireNonNull(other, "other is null");
         return Observable.wrap(other).concatWith(this.toObservable());
     }
@@ -2800,7 +2800,7 @@ public final <T> Observable<T> startWith(@NonNull ObservableSource<T> other) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T> Flowable<T> startWith(@NonNull Publisher<T> other) {
+    public final <@NonNull T> Flowable<T> startWith(@NonNull Publisher<T> other) {
         Objects.requireNonNull(other, "other is null");
         return this.<T>toFlowable().startWith(other);
     }
@@ -3214,7 +3214,7 @@ public final <R> R to(@NonNull CompletableConverter<? extends R> converter) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T> Flowable<T> toFlowable() {
+    public final <@NonNull T> Flowable<T> toFlowable() {
         if (this instanceof FuseToFlowable) {
             return ((FuseToFlowable<T>)this).fuseToFlowable();
         }
@@ -3259,7 +3259,7 @@ public final Future<Void> toFuture() {
     @SuppressWarnings("unchecked")
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T> Maybe<T> toMaybe() {
+    public final <@NonNull T> Maybe<T> toMaybe() {
         if (this instanceof FuseToMaybe) {
             return ((FuseToMaybe<T>)this).fuseToMaybe();
         }
@@ -3282,7 +3282,7 @@ public final <T> Maybe<T> toMaybe() {
     @SuppressWarnings("unchecked")
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T> Observable<T> toObservable() {
+    public final <@NonNull T> Observable<T> toObservable() {
         if (this instanceof FuseToObservable) {
             return ((FuseToObservable<T>)this).fuseToObservable();
         }
@@ -3469,7 +3469,7 @@ public static Completable fromCompletionStage(@NonNull CompletionStage<?> stage)
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T> CompletionStage<T> toCompletionStage(@Nullable T defaultItem) {
+    public final <@Nullable T> CompletionStage<T> toCompletionStage(T defaultItem) {
         return subscribeWith(new CompletionStageConsumer<>(true, defaultItem));
     }
 }
diff --git a/src/main/java/io/reactivex/rxjava3/core/Flowable.java b/src/main/java/io/reactivex/rxjava3/core/Flowable.java
index d22d8dc4dc..31827d9e1c 100644
--- a/src/main/java/io/reactivex/rxjava3/core/Flowable.java
+++ b/src/main/java/io/reactivex/rxjava3/core/Flowable.java
@@ -193,7 +193,7 @@ public abstract class Flowable<@NonNull T> implements Publisher<T> {
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> amb(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> amb(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableAmb<>(null, sources));
     }
@@ -232,7 +232,7 @@ public static <T> Flowable<T> amb(@NonNull Iterable<@NonNull ? extends Publisher
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> ambArray(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> ambArray(@NonNull Publisher<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         int len = sources.length;
         if (len == 0) {
@@ -296,7 +296,7 @@ public static int bufferSize() {
     @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public static <T, @NonNull R> Flowable<R> combineLatestArray(@NonNull Publisher<@NonNull ? extends T>[] sources, @NonNull Function<? super Object[], ? extends R> combiner) {
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatestArray(@NonNull Publisher<? extends T>[] sources, @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatestArray(sources, combiner, bufferSize());
     }
 
@@ -344,7 +344,7 @@ public static int bufferSize() {
     @CheckReturnValue
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <T, R> Flowable<R> combineLatestArray(@NonNull Publisher<@NonNull ? extends T>[] sources, @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatestArray(@NonNull Publisher<? extends T>[] sources, @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -395,7 +395,7 @@ public static <T, R> Flowable<R> combineLatestArray(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public static <T, @NonNull R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatest(sources, combiner, bufferSize());
     }
@@ -444,7 +444,7 @@ public static <T, R> Flowable<R> combineLatestArray(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <T, R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -493,7 +493,7 @@ public static <T, R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? exte
     @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public static <T, @NonNull R> Flowable<R> combineLatestArrayDelayError(@NonNull Publisher<@NonNull ? extends T>[] sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatestArrayDelayError(@NonNull Publisher<? extends T>[] sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatestArrayDelayError(sources, combiner, bufferSize());
     }
@@ -543,7 +543,7 @@ public static <T, R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? exte
     @CheckReturnValue
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <T, @NonNull R> Flowable<R> combineLatestArrayDelayError(@NonNull Publisher<@NonNull ? extends T>[] sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatestArrayDelayError(@NonNull Publisher<? extends T>[] sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -596,7 +596,7 @@ public static <T, R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? exte
     @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public static <T, @NonNull R> Flowable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatestDelayError(sources, combiner, bufferSize());
     }
@@ -646,7 +646,7 @@ public static <T, R> Flowable<R> combineLatest(@NonNull Iterable<@NonNull ? exte
     @CheckReturnValue
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public static <T, R> Flowable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -691,8 +691,8 @@ public static <T, R> Flowable<R> combineLatestDelayError(@NonNull Iterable<@NonN
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -740,9 +740,9 @@ public static <T1, T2, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3,
             @NonNull Function3<? super T1, ? super T2, ? super T3, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -795,9 +795,9 @@ public static <T1, T2, T3, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3, @NonNull Publisher<@NonNull ? extends T4> source4,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3, @NonNull Publisher<? extends T4> source4,
             @NonNull Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -854,10 +854,10 @@ public static <T1, T2, T3, T4, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3, @NonNull Publisher<@NonNull ? extends T4> source4,
-            @NonNull Publisher<@NonNull ? extends T5> source5,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3, @NonNull Publisher<? extends T4> source4,
+            @NonNull Publisher<? extends T5> source5,
             @NonNull Function5<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -918,10 +918,10 @@ public static <T1, T2, T3, T4, T5, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3, @NonNull Publisher<@NonNull ? extends T4> source4,
-            @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3, @NonNull Publisher<? extends T4> source4,
+            @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
             @NonNull Function6<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -987,11 +987,11 @@ public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3, @NonNull Publisher<@NonNull ? extends T4> source4,
-            @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
-            @NonNull Publisher<@NonNull ? extends T7> source7,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3, @NonNull Publisher<? extends T4> source4,
+            @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
+            @NonNull Publisher<? extends T7> source7,
             @NonNull Function7<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -1061,11 +1061,11 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3, @NonNull Publisher<@NonNull ? extends T4> source4,
-            @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
-            @NonNull Publisher<@NonNull ? extends T7> source7, @NonNull Publisher<@NonNull ? extends T8> source8,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3, @NonNull Publisher<? extends T4> source4,
+            @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
+            @NonNull Publisher<? extends T7> source7, @NonNull Publisher<? extends T8> source8,
             @NonNull Function8<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? super T8, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -1140,12 +1140,12 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> combineLatest(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
-            @NonNull Publisher<@NonNull ? extends T3> source3, @NonNull Publisher<@NonNull ? extends T4> source4,
-            @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
-            @NonNull Publisher<@NonNull ? extends T7> source7, @NonNull Publisher<@NonNull ? extends T8> source8,
-            @NonNull Publisher<@NonNull ? extends T9> source9,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull T9, @NonNull R> Flowable<R> combineLatest(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
+            @NonNull Publisher<? extends T3> source3, @NonNull Publisher<? extends T4> source4,
+            @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
+            @NonNull Publisher<? extends T7> source7, @NonNull Publisher<? extends T8> source8,
+            @NonNull Publisher<? extends T9> source9,
             @NonNull Function9<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? super T8, ? super T9, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -1184,7 +1184,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> combineLatest(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         // unlike general sources, fromIterable can only throw on a boundary because it is consumed only there
         return fromIterable(sources).concatMapDelayError((Function)Functions.identity(), false, 2);
@@ -1216,7 +1216,7 @@ public static <T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends Publis
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return concat(sources, bufferSize());
     }
 
@@ -1250,7 +1250,7 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Publi
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int prefetch) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int prefetch) {
         return fromPublisher(sources).concatMap((Function)Functions.identity(), prefetch);
     }
 
@@ -1282,7 +1282,7 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Publi
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return concatArray(source1, source2);
@@ -1318,9 +1318,9 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends T> so
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
-            @NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2,
-            @NonNull Publisher<@NonNull ? extends T> source3) {
+    public static <@NonNull T> Flowable<T> concat(
+            @NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2,
+            @NonNull Publisher<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         Objects.requireNonNull(source3, "source3 is null");
@@ -1359,9 +1359,9 @@ public static <T> Flowable<T> concat(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
-            @NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2,
-            @NonNull Publisher<@NonNull ? extends T> source3, @NonNull Publisher<@NonNull ? extends T> source4) {
+    public static <@NonNull T> Flowable<T> concat(
+            @NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2,
+            @NonNull Publisher<? extends T> source3, @NonNull Publisher<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         Objects.requireNonNull(source3, "source3 is null");
@@ -1394,7 +1394,7 @@ public static <T> Flowable<T> concat(
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> concatArray(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArray(@NonNull Publisher<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -1429,7 +1429,7 @@ public static <T> Flowable<T> concatArray(@NonNull Publisher<@NonNull ? extends
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> concatArrayDelayError(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayDelayError(@NonNull Publisher<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -1468,7 +1468,7 @@ public static <T> Flowable<T> concatArrayDelayError(@NonNull Publisher<@NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> concatArrayEager(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEager(@NonNull Publisher<? extends T>... sources) {
         return concatArrayEager(bufferSize(), bufferSize(), sources);
     }
 
@@ -1505,7 +1505,7 @@ public static <T> Flowable<T> concatArrayEager(@NonNull Publisher<@NonNull ? ext
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @SafeVarargs
-    public static <T> Flowable<T> concatArrayEager(int maxConcurrency, int prefetch, @NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEager(int maxConcurrency, int prefetch, @NonNull Publisher<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -1541,7 +1541,7 @@ public static <T> Flowable<T> concatArrayEager(int maxConcurrency, int prefetch,
     @BackpressureSupport(BackpressureKind.FULL)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> concatArrayEagerDelayError(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEagerDelayError(@NonNull Publisher<? extends T>... sources) {
         return concatArrayEagerDelayError(bufferSize(), bufferSize(), sources);
     }
 
@@ -1579,7 +1579,7 @@ public static <T> Flowable<T> concatArrayEagerDelayError(@NonNull Publisher<@Non
     @BackpressureSupport(BackpressureKind.FULL)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> concatArrayEagerDelayError(int maxConcurrency, int prefetch, @NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEagerDelayError(int maxConcurrency, int prefetch, @NonNull Publisher<? extends T>... sources) {
         return fromArray(sources).concatMapEagerDelayError((Function)Functions.identity(), true, maxConcurrency, prefetch);
     }
 
@@ -1607,7 +1607,7 @@ public static <T> Flowable<T> concatArrayEagerDelayError(int maxConcurrency, int
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return fromIterable(sources).concatMapDelayError((Function)Functions.identity());
     }
@@ -1632,7 +1632,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? exte
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return concatDelayError(sources, bufferSize(), true);
     }
 
@@ -1661,7 +1661,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? ext
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int prefetch, boolean tillTheEnd) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int prefetch, boolean tillTheEnd) {
         return fromPublisher(sources).concatMapDelayError((Function)Functions.identity(), tillTheEnd, prefetch);
     }
 
@@ -1691,7 +1691,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? ext
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         return concatEager(sources, bufferSize(), bufferSize());
     }
 
@@ -1727,7 +1727,7 @@ public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends P
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
-    public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency, int prefetch) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency, int prefetch) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -1760,7 +1760,7 @@ public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends P
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return concatEager(sources, bufferSize(), bufferSize());
     }
 
@@ -1796,7 +1796,7 @@ public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
-    public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency, int prefetch) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency, int prefetch) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -1830,7 +1830,7 @@ public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         return concatEagerDelayError(sources, bufferSize(), bufferSize());
     }
 
@@ -1867,7 +1867,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ?
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency, int prefetch) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency, int prefetch) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -1901,7 +1901,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ?
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return concatEagerDelayError(sources, bufferSize(), bufferSize());
     }
 
@@ -1938,7 +1938,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "rawtypes", "unchecked" })
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency, int prefetch) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency, int prefetch) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -2003,7 +2003,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull
     @NonNull
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> create(@NonNull FlowableOnSubscribe<T> source, @NonNull BackpressureStrategy mode) {
+    public static <@NonNull T> Flowable<T> create(@NonNull FlowableOnSubscribe<T> source, @NonNull BackpressureStrategy mode) {
         Objects.requireNonNull(source, "source is null");
         Objects.requireNonNull(mode, "mode is null");
         return RxJavaPlugins.onAssembly(new FlowableCreate<>(source, mode));
@@ -2040,7 +2040,7 @@ public static <T> Flowable<T> create(@NonNull FlowableOnSubscribe<T> source, @No
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> defer(@NonNull Supplier<? extends Publisher<@NonNull ? extends T>> supplier) {
+    public static <@NonNull T> Flowable<T> defer(@NonNull Supplier<? extends Publisher<? extends T>> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new FlowableDefer<>(supplier));
     }
@@ -2067,7 +2067,7 @@ public static <T> Flowable<T> defer(@NonNull Supplier<? extends Publisher<@NonNu
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Flowable<T> empty() {
+    public static <@NonNull T> Flowable<T> empty() {
         return RxJavaPlugins.onAssembly((Flowable<T>) FlowableEmpty.INSTANCE);
     }
 
@@ -2095,7 +2095,7 @@ public static <T> Flowable<T> empty() {
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> error(@NonNull Supplier<? extends Throwable> supplier) {
+    public static <@NonNull T> Flowable<T> error(@NonNull Supplier<? extends Throwable> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new FlowableError<>(supplier));
     }
@@ -2124,7 +2124,7 @@ public static <T> Flowable<T> error(@NonNull Supplier<? extends Throwable> suppl
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> error(@NonNull Throwable throwable) {
+    public static <@NonNull T> Flowable<T> error(@NonNull Throwable throwable) {
         Objects.requireNonNull(throwable, "throwable is null");
         return error(Functions.justSupplier(throwable));
     }
@@ -2157,7 +2157,7 @@ public static <T> Flowable<T> error(@NonNull Throwable throwable) {
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public static <T> Flowable<T> fromAction(@NonNull Action action) {
+    public static <@NonNull T> Flowable<T> fromAction(@NonNull Action action) {
         Objects.requireNonNull(action, "action is null");
         return RxJavaPlugins.onAssembly(new FlowableFromAction<>(action));
     }
@@ -2259,7 +2259,7 @@ public static <T> Flowable<T> fromAction(@NonNull Action action) {
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public static <T> Flowable<T> fromCompletable(@NonNull CompletableSource completableSource) {
+    public static <@NonNull T> Flowable<T> fromCompletable(@NonNull CompletableSource completableSource) {
         Objects.requireNonNull(completableSource, "completableSource is null");
         return RxJavaPlugins.onAssembly(new FlowableFromCompletable<>(completableSource));
     }
@@ -2379,7 +2379,7 @@ public static <T> Flowable<T> fromCompletable(@NonNull CompletableSource complet
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <@NonNull T> Flowable<T> fromIterable(@NonNull Iterable<@NonNull ? extends T> source) {
+    public static <@NonNull T> Flowable<T> fromIterable(@NonNull Iterable<? extends T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new FlowableFromIterable<>(source));
     }
@@ -2406,7 +2406,7 @@ public static <T> Flowable<T> fromCompletable(@NonNull CompletableSource complet
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <T> Flowable<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
+    public static <@NonNull T> Flowable<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
         Objects.requireNonNull(maybe, "maybe is null");
         return RxJavaPlugins.onAssembly(new MaybeToFlowable<>(maybe));
     }
@@ -2454,7 +2454,7 @@ public static <T> Flowable<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> fromObservable(@NonNull ObservableSource<T> source, @NonNull BackpressureStrategy strategy) {
+    public static <@NonNull T> Flowable<T> fromObservable(@NonNull ObservableSource<T> source, @NonNull BackpressureStrategy strategy) {
         Objects.requireNonNull(source, "source is null");
         Objects.requireNonNull(strategy, "strategy is null");
         Flowable<T> f = new FlowableFromObservable<>(source);
@@ -2504,7 +2504,7 @@ public static <T> Flowable<T> fromObservable(@NonNull ObservableSource<T> source
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
-    public static <T> Flowable<T> fromPublisher(@NonNull Publisher<@NonNull ? extends T> publisher) {
+    public static <@NonNull T> Flowable<T> fromPublisher(@NonNull Publisher<? extends T> publisher) {
         if (publisher instanceof Flowable) {
             return RxJavaPlugins.onAssembly((Flowable<T>)publisher);
         }
@@ -2547,7 +2547,7 @@ public static <T> Flowable<T> fromPublisher(@NonNull Publisher<@NonNull ? extend
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public static <T> Flowable<T> fromRunnable(@NonNull Runnable run) {
+    public static <@NonNull T> Flowable<T> fromRunnable(@NonNull Runnable run) {
         Objects.requireNonNull(run, "run is null");
         return RxJavaPlugins.onAssembly(new FlowableFromRunnable<>(run));
     }
@@ -2573,7 +2573,7 @@ public static <T> Flowable<T> fromRunnable(@NonNull Runnable run) {
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <T> Flowable<T> fromSingle(@NonNull SingleSource<T> source) {
+    public static <@NonNull T> Flowable<T> fromSingle(@NonNull SingleSource<T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new SingleToFlowable<>(source));
     }
@@ -2646,7 +2646,7 @@ public static <T> Flowable<T> fromSingle(@NonNull SingleSource<T> source) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> generate(@NonNull Consumer<@NonNull Emitter<T>> generator) {
+    public static <@NonNull T> Flowable<T> generate(@NonNull Consumer<@NonNull Emitter<T>> generator) {
         Objects.requireNonNull(generator, "generator is null");
         return generate(Functions.nullSupplier(),
                 FlowableInternalHelper.simpleGenerator(generator),
@@ -2681,7 +2681,7 @@ public static <T> Flowable<T> generate(@NonNull Consumer<@NonNull Emitter<T>> ge
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiConsumer<S, Emitter<T>> generator) {
+    public static <@NonNull T, @NonNull S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiConsumer<S, Emitter<T>> generator) {
         Objects.requireNonNull(generator, "generator is null");
         return generate(initialState, FlowableInternalHelper.simpleBiGenerator(generator),
                 Functions.emptyConsumer());
@@ -2717,7 +2717,7 @@ public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @No
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiConsumer<S, Emitter<T>> generator,
+    public static <@NonNull T, @NonNull S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiConsumer<S, Emitter<T>> generator,
             @NonNull Consumer<? super S> disposeState) {
         Objects.requireNonNull(generator, "generator is null");
         return generate(initialState, FlowableInternalHelper.simpleBiGenerator(generator), disposeState);
@@ -2752,7 +2752,7 @@ public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @No
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, @NonNull Emitter<T>, S> generator) {
+    public static <@NonNull T, @NonNull S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, @NonNull Emitter<T>, S> generator) {
         return generate(initialState, generator, Functions.emptyConsumer());
     }
 
@@ -2787,7 +2787,7 @@ public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @No
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, @NonNull Emitter<T>, S> generator, @NonNull Consumer<? super S> disposeState) {
+    public static <@NonNull T, @NonNull S> Flowable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, @NonNull Emitter<T>, S> generator, @NonNull Consumer<? super S> disposeState) {
         Objects.requireNonNull(initialState, "initialState is null");
         Objects.requireNonNull(generator, "generator is null");
         Objects.requireNonNull(disposeState, "disposeState is null");
@@ -3494,7 +3494,7 @@ public static Flowable<Long> intervalRange(long start, long count, long initialD
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), false, maxConcurrency, bufferSize);
     }
 
@@ -3547,7 +3547,7 @@ public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publish
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> mergeArray(int maxConcurrency, int bufferSize, @NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArray(int maxConcurrency, int bufferSize, @NonNull Publisher<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), false, maxConcurrency, bufferSize);
     }
 
@@ -3592,7 +3592,7 @@ public static <T> Flowable<T> mergeArray(int maxConcurrency, int bufferSize, @No
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         return fromIterable(sources).flatMap((Function)Functions.identity());
     }
 
@@ -3642,7 +3642,7 @@ public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publish
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), maxConcurrency);
     }
 
@@ -3688,7 +3688,7 @@ public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends Publish
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return merge(sources, bufferSize());
     }
 
@@ -3740,7 +3740,7 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Publis
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency) {
         return fromPublisher(sources).flatMap((Function)Functions.identity(), maxConcurrency);
     }
 
@@ -3786,7 +3786,7 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Publis
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> mergeArray(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArray(@NonNull Publisher<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), sources.length);
     }
 
@@ -3833,7 +3833,7 @@ public static <T> Flowable<T> mergeArray(@NonNull Publisher<@NonNull ? extends T
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return fromArray(source1, source2).flatMap((Function)Functions.identity(), false, 2);
@@ -3884,7 +3884,7 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends T> sou
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2, @NonNull Publisher<@NonNull ? extends T> source3) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2, @NonNull Publisher<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         Objects.requireNonNull(source3, "source3 is null");
@@ -3938,9 +3938,9 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends T> sou
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
-            @NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2,
-            @NonNull Publisher<@NonNull ? extends T> source3, @NonNull Publisher<@NonNull ? extends T> source4) {
+    public static <@NonNull T> Flowable<T> merge(
+            @NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2,
+            @NonNull Publisher<? extends T> source3, @NonNull Publisher<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         Objects.requireNonNull(source3, "source3 is null");
@@ -3981,7 +3981,7 @@ public static <T> Flowable<T> merge(
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true);
     }
 
@@ -4023,7 +4023,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? exten
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -4066,7 +4066,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? exten
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> mergeArrayDelayError(int maxConcurrency, int bufferSize, @NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArrayDelayError(int maxConcurrency, int bufferSize, @NonNull Publisher<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -4106,7 +4106,7 @@ public static <T> Flowable<T> mergeArrayDelayError(int maxConcurrency, int buffe
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true, maxConcurrency);
     }
 
@@ -4143,7 +4143,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? exten
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return mergeDelayError(sources, bufferSize());
     }
 
@@ -4185,7 +4185,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int maxConcurrency) {
         return fromPublisher(sources).flatMap((Function)Functions.identity(), true, maxConcurrency);
     }
 
@@ -4223,7 +4223,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> mergeArrayDelayError(@NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArrayDelayError(@NonNull Publisher<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), true, sources.length);
     }
 
@@ -4262,7 +4262,7 @@ public static <T> Flowable<T> mergeArrayDelayError(@NonNull Publisher<@NonNull ?
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return fromArray(source1, source2).flatMap((Function)Functions.identity(), true, 2);
@@ -4306,7 +4306,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2, @NonNull Publisher<@NonNull ? extends T> source3) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2, @NonNull Publisher<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         Objects.requireNonNull(source3, "source3 is null");
@@ -4353,9 +4353,9 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(
-            @NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2,
-            @NonNull Publisher<@NonNull ? extends T> source3, @NonNull Publisher<@NonNull ? extends T> source4) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(
+            @NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2,
+            @NonNull Publisher<? extends T> source3, @NonNull Publisher<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         Objects.requireNonNull(source3, "source3 is null");
@@ -4386,7 +4386,7 @@ public static <T> Flowable<T> mergeDelayError(
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Flowable<T> never() {
+    public static <@NonNull T> Flowable<T> never() {
         return RxJavaPlugins.onAssembly((Flowable<T>) FlowableNever.INSTANCE);
     }
 
@@ -4506,7 +4506,7 @@ public static Flowable<Long> rangeLong(long start, long count) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2) {
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate(), bufferSize());
     }
 
@@ -4540,7 +4540,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? ex
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2,
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2,
             @NonNull BiPredicate<? super T, ? super T> isEqual) {
         return sequenceEqual(source1, source2, isEqual, bufferSize());
     }
@@ -4578,7 +4578,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? ex
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2,
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2,
             @NonNull BiPredicate<? super T, ? super T> isEqual, int bufferSize) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -4617,7 +4617,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? ex
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? extends T> source1, @NonNull Publisher<@NonNull ? extends T> source2, int bufferSize) {
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull Publisher<? extends T> source1, @NonNull Publisher<? extends T> source2, int bufferSize) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate(), bufferSize);
     }
 
@@ -4659,7 +4659,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull Publisher<@NonNull ? ex
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int bufferSize) {
+    public static <@NonNull T> Flowable<T> switchOnNext(@NonNull Publisher<? extends Publisher<? extends T>> sources, int bufferSize) {
         return fromPublisher(sources).switchMap((Function)Functions.identity(), bufferSize);
     }
 
@@ -4698,7 +4698,7 @@ public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return fromPublisher(sources).switchMap((Function)Functions.identity());
     }
 
@@ -4738,7 +4738,7 @@ public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources) {
         return switchOnNextDelayError(sources, bufferSize());
     }
 
@@ -4781,8 +4781,8 @@ public static <T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, int prefetch) {
-        return fromPublisher(sources).switchMapDelayError(Functions.<Publisher<@NonNull ? extends T>>identity(), prefetch);
+    public static <@NonNull T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends Publisher<? extends T>> sources, int prefetch) {
+        return fromPublisher(sources).switchMapDelayError(Functions.<Publisher<? extends T>>identity(), prefetch);
     }
 
     /**
@@ -4870,7 +4870,7 @@ public static Flowable<Long> timer(long delay, @NonNull TimeUnit unit, @NonNull
     @NonNull
     @BackpressureSupport(BackpressureKind.NONE)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> unsafeCreate(@NonNull Publisher<T> onSubscribe) {
+    public static <@NonNull T> Flowable<T> unsafeCreate(@NonNull Publisher<T> onSubscribe) {
         Objects.requireNonNull(onSubscribe, "onSubscribe is null");
         if (onSubscribe instanceof Flowable) {
             throw new IllegalArgumentException("unsafeCreate(Flowable) should be upgraded");
@@ -4908,9 +4908,9 @@ public static <T> Flowable<T> unsafeCreate(@NonNull Publisher<T> onSubscribe) {
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, D> Flowable<T> using(
+    public static <@NonNull T, @NonNull D> Flowable<T> using(
             @NonNull Supplier<? extends D> resourceSupplier,
-            @NonNull Function<? super D, ? extends Publisher<@NonNull ? extends T>> sourceSupplier,
+            @NonNull Function<? super D, @NonNull ? extends Publisher<? extends T>> sourceSupplier,
             @NonNull Consumer<? super D> resourceCleanup) {
         return using(resourceSupplier, sourceSupplier, resourceCleanup, true);
     }
@@ -4951,9 +4951,9 @@ public static <T, D> Flowable<T> using(
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, D> Flowable<T> using(
+    public static <@NonNull T, @NonNull D> Flowable<T> using(
             @NonNull Supplier<? extends D> resourceSupplier,
-            @NonNull Function<? super D, ? extends Publisher<@NonNull ? extends T>> sourceSupplier,
+            @NonNull Function<? super D, @NonNull ? extends Publisher<? extends T>> sourceSupplier,
             @NonNull Consumer<? super D> resourceCleanup,
             boolean eager) {
         Objects.requireNonNull(resourceSupplier, "resourceSupplier is null");
@@ -5011,7 +5011,7 @@ public static <T, D> Flowable<T> using(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Flowable<R> zip(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources, @NonNull Function<? super Object[], ? extends R> zipper) {
+    public static <@NonNull T, @NonNull R> Flowable<R> zip(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources, @NonNull Function<? super Object[], ? extends R> zipper) {
         Objects.requireNonNull(zipper, "zipper is null");
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableZip<>(null, sources, zipper, bufferSize(), false));
@@ -5072,7 +5072,7 @@ public static <T, R> Flowable<R> zip(@NonNull Iterable<@NonNull ? extends Publis
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Flowable<R> zip(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Flowable<R> zip(@NonNull Iterable<@NonNull ? extends Publisher<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> zipper, boolean delayError,
             int bufferSize) {
         Objects.requireNonNull(zipper, "zipper is null");
@@ -5134,8 +5134,8 @@ public static <T, R> Flowable<R> zip(@NonNull Iterable<@NonNull ? extends Publis
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5197,8 +5197,8 @@ public static <T1, T2, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper, boolean delayError) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5262,8 +5262,8 @@ public static <T1, T2, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2,
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper, boolean delayError, int bufferSize) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5328,8 +5328,8 @@ public static <T1, T2, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
             @NonNull Function3<? super T1, ? super T2, ? super T3, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5399,9 +5399,9 @@ public static <T1, T2, T3, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
-            @NonNull Publisher<@NonNull ? extends T4> source4,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
+            @NonNull Publisher<? extends T4> source4,
             @NonNull Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5475,9 +5475,9 @@ public static <T1, T2, T3, T4, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
-            @NonNull Publisher<@NonNull ? extends T4> source4, @NonNull Publisher<@NonNull ? extends T5> source5,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
+            @NonNull Publisher<? extends T4> source4, @NonNull Publisher<? extends T5> source5,
             @NonNull Function5<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5555,9 +5555,9 @@ public static <T1, T2, T3, T4, T5, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
-            @NonNull Publisher<@NonNull ? extends T4> source4, @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
+            @NonNull Publisher<? extends T4> source4, @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
             @NonNull Function6<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5639,10 +5639,10 @@ public static <T1, T2, T3, T4, T5, T6, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
-            @NonNull Publisher<@NonNull ? extends T4> source4, @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
-            @NonNull Publisher<@NonNull ? extends T7> source7,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
+            @NonNull Publisher<? extends T4> source4, @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
+            @NonNull Publisher<? extends T7> source7,
             @NonNull Function7<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5728,10 +5728,10 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
-            @NonNull Publisher<@NonNull ? extends T4> source4, @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
-            @NonNull Publisher<@NonNull ? extends T7> source7, @NonNull Publisher<@NonNull ? extends T8> source8,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
+            @NonNull Publisher<? extends T4> source4, @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
+            @NonNull Publisher<? extends T7> source7, @NonNull Publisher<? extends T8> source8,
             @NonNull Function8<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? super T8, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -5822,10 +5822,10 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Flowable<R> zip(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> zip(
-            @NonNull Publisher<@NonNull ? extends T1> source1, @NonNull Publisher<@NonNull ? extends T2> source2, @NonNull Publisher<@NonNull ? extends T3> source3,
-            @NonNull Publisher<@NonNull ? extends T4> source4, @NonNull Publisher<@NonNull ? extends T5> source5, @NonNull Publisher<@NonNull ? extends T6> source6,
-            @NonNull Publisher<@NonNull ? extends T7> source7, @NonNull Publisher<@NonNull ? extends T8> source8, @NonNull Publisher<@NonNull ? extends T9> source9,
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull T9, @NonNull R> Flowable<R> zip(
+            @NonNull Publisher<? extends T1> source1, @NonNull Publisher<? extends T2> source2, @NonNull Publisher<? extends T3> source3,
+            @NonNull Publisher<? extends T4> source4, @NonNull Publisher<? extends T5> source5, @NonNull Publisher<? extends T6> source6,
+            @NonNull Publisher<? extends T7> source7, @NonNull Publisher<? extends T8> source8, @NonNull Publisher<? extends T9> source9,
             @NonNull Function9<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? super T8, ? super T9, ? extends R> zipper) {
 
         Objects.requireNonNull(source1, "source1 is null");
@@ -5897,8 +5897,8 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Flowable<R> zip(
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T, R> Flowable<R> zipArray(@NonNull Function<? super Object[], ? extends R> zipper,
-            boolean delayError, int bufferSize, @NonNull Publisher<@NonNull ? extends T>... sources) {
+    public static <@NonNull T, @NonNull R> Flowable<R> zipArray(@NonNull Function<? super Object[], ? extends R> zipper,
+            boolean delayError, int bufferSize, @NonNull Publisher<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -5973,7 +5973,7 @@ public final Single<Boolean> all(@NonNull Predicate<? super T> predicate) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> ambWith(@NonNull Publisher<@NonNull ? extends T> other) {
+    public final Flowable<T> ambWith(@NonNull Publisher<? extends T> other) {
         Objects.requireNonNull(other, "other is null");
         return ambArray(this, other);
     }
@@ -6681,7 +6681,7 @@ public final void blockingSubscribe(@NonNull Consumer<? super T> onNext, @NonNul
      */
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final void blockingSubscribe(@NonNull Subscriber<@NonNull ? super T> subscriber) {
+    public final void blockingSubscribe(@NonNull Subscriber<? super T> subscriber) {
         Objects.requireNonNull(subscriber, "subscriber is null");
         FlowableBlockingSubscribe.subscribe(this, subscriber);
     }
@@ -6788,7 +6788,7 @@ public final Flowable<List<T>> buffer(int count, int skip) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U extends Collection<? super T>> Flowable<U> buffer(int count, int skip, @NonNull Supplier<U> bufferSupplier) {
+    public final <@NonNull U extends Collection<? super T>> Flowable<U> buffer(int count, int skip, @NonNull Supplier<U> bufferSupplier) {
         ObjectHelper.verifyPositive(count, "count");
         ObjectHelper.verifyPositive(skip, "skip");
         Objects.requireNonNull(bufferSupplier, "bufferSupplier is null");
@@ -6827,7 +6827,7 @@ public final <U extends Collection<? super T>> Flowable<U> buffer(int count, int
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U extends Collection<? super T>> Flowable<U> buffer(int count, @NonNull Supplier<U> bufferSupplier) {
+    public final <@NonNull U extends Collection<? super T>> Flowable<U> buffer(int count, @NonNull Supplier<U> bufferSupplier) {
         return buffer(count, count, bufferSupplier);
     }
 
@@ -6942,7 +6942,7 @@ public final Flowable<List<T>> buffer(long timespan, long timeskip, @NonNull Tim
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <U extends Collection<? super T>> Flowable<U> buffer(long timespan, long timeskip, @NonNull TimeUnit unit,
+    public final <@NonNull U extends Collection<? super T>> Flowable<U> buffer(long timespan, long timeskip, @NonNull TimeUnit unit,
             @NonNull Scheduler scheduler, @NonNull Supplier<U> bufferSupplier) {
         Objects.requireNonNull(unit, "unit is null");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -7103,7 +7103,7 @@ public final Flowable<List<T>> buffer(long timespan, @NonNull TimeUnit unit, @No
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <U extends Collection<? super T>> Flowable<U> buffer(
+    public final <@NonNull U extends Collection<? super T>> Flowable<U> buffer(
             long timespan, @NonNull TimeUnit unit,
             @NonNull Scheduler scheduler, int count,
             @NonNull Supplier<U> bufferSupplier,
@@ -7182,9 +7182,9 @@ public final Flowable<List<T>> buffer(long timespan, @NonNull TimeUnit unit, @No
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <TOpening, TClosing> Flowable<List<T>> buffer(
-            @NonNull Publisher<@NonNull ? extends TOpening> openingIndicator,
-            @NonNull Function<? super TOpening, ? extends Publisher<@NonNull ? extends TClosing>> closingIndicator) {
+    public final <@NonNull TOpening, @NonNull TClosing> Flowable<List<T>> buffer(
+            @NonNull Publisher<? extends TOpening> openingIndicator,
+            @NonNull Function<? super TOpening, @NonNull ? extends Publisher<? extends TClosing>> closingIndicator) {
         return buffer(openingIndicator, closingIndicator, ArrayListSupplier.asSupplier());
     }
 
@@ -7223,9 +7223,9 @@ public final <TOpening, TClosing> Flowable<List<T>> buffer(
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <TOpening, TClosing, U extends Collection<? super T>> Flowable<U> buffer(
-            @NonNull Publisher<@NonNull ? extends TOpening> openingIndicator,
-            @NonNull Function<? super TOpening, ? extends Publisher<@NonNull ? extends TClosing>> closingIndicator,
+    public final <@NonNull TOpening, @NonNull TClosing, @NonNull U extends Collection<? super T>> Flowable<U> buffer(
+            @NonNull Publisher<? extends TOpening> openingIndicator,
+            @NonNull Function<? super TOpening, @NonNull ? extends Publisher<? extends TClosing>> closingIndicator,
             @NonNull Supplier<U> bufferSupplier) {
         Objects.requireNonNull(openingIndicator, "openingIndicator is null");
         Objects.requireNonNull(closingIndicator, "closingIndicator is null");
@@ -7264,7 +7264,7 @@ public final <TOpening, TClosing, U extends Collection<? super T>> Flowable<U> b
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Flowable<List<T>> buffer(@NonNull Publisher<B> boundaryIndicator) {
+    public final <@NonNull B> Flowable<List<T>> buffer(@NonNull Publisher<B> boundaryIndicator) {
         return buffer(boundaryIndicator, ArrayListSupplier.asSupplier());
     }
 
@@ -7302,7 +7302,7 @@ public final <B> Flowable<List<T>> buffer(@NonNull Publisher<B> boundaryIndicato
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Flowable<List<T>> buffer(@NonNull Publisher<B> boundaryIndicator, int initialCapacity) {
+    public final <@NonNull B> Flowable<List<T>> buffer(@NonNull Publisher<B> boundaryIndicator, int initialCapacity) {
         ObjectHelper.verifyPositive(initialCapacity, "initialCapacity");
         return buffer(boundaryIndicator, Functions.createArrayList(initialCapacity));
     }
@@ -7342,7 +7342,7 @@ public final <B> Flowable<List<T>> buffer(@NonNull Publisher<B> boundaryIndicato
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B, U extends Collection<? super T>> Flowable<U> buffer(@NonNull Publisher<B> boundaryIndicator, @NonNull Supplier<U> bufferSupplier) {
+    public final <@NonNull B, @NonNull U extends Collection<? super T>> Flowable<U> buffer(@NonNull Publisher<B> boundaryIndicator, @NonNull Supplier<U> bufferSupplier) {
         Objects.requireNonNull(boundaryIndicator, "boundaryIndicator is null");
         Objects.requireNonNull(bufferSupplier, "bufferSupplier is null");
         return RxJavaPlugins.onAssembly(new FlowableBufferExactBoundary<>(this, boundaryIndicator, bufferSupplier));
@@ -7499,7 +7499,7 @@ public final Flowable<T> cacheWithInitialCapacity(int initialCapacity) {
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<U> cast(@NonNull Class<U> clazz) {
+    public final <@NonNull U> Flowable<U> cast(@NonNull Class<U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return map(Functions.castFunction(clazz));
     }
@@ -7538,7 +7538,7 @@ public final <U> Flowable<U> cast(@NonNull Class<U> clazz) {
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Single<U> collect(@NonNull Supplier<? extends U> initialItemSupplier, @NonNull BiConsumer<? super U, ? super T> collector) {
+    public final <@NonNull U> Single<U> collect(@NonNull Supplier<? extends U> initialItemSupplier, @NonNull BiConsumer<? super U, ? super T> collector) {
         Objects.requireNonNull(initialItemSupplier, "initialItemSupplier is null");
         Objects.requireNonNull(collector, "collector is null");
         return RxJavaPlugins.onAssembly(new FlowableCollectSingle<>(this, initialItemSupplier, collector));
@@ -7610,7 +7610,7 @@ public final <U> Single<U> collect(@NonNull Supplier<? extends U> initialItemSup
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> compose(@NonNull FlowableTransformer<? super T, ? extends R> composer) {
+    public final <@NonNull R> Flowable<R> compose(@NonNull FlowableTransformer<? super T, ? extends R> composer) {
         return fromPublisher(((FlowableTransformer<T, R>) Objects.requireNonNull(composer, "composer is null")).apply(this));
     }
 
@@ -7647,7 +7647,7 @@ public final <R> Flowable<R> compose(@NonNull FlowableTransformer<? super T, ? e
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return concatMap(mapper, 2);
     }
 
@@ -7688,7 +7688,7 @@ public final <R> Flowable<R> concatMap(@NonNull Function<? super T, ? extends Pu
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, int prefetch) {
+    public final <@NonNull R> Flowable<R> concatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         if (this instanceof ScalarSupplier) {
@@ -7742,7 +7742,7 @@ public final <R> Flowable<R> concatMap(@NonNull Function<? super T, ? extends Pu
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <R> Flowable<R> concatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, int prefetch, @NonNull Scheduler scheduler) {
+    public final <@NonNull R> Flowable<R> concatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, int prefetch, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -7953,7 +7953,7 @@ public final Completable concatMapCompletableDelayError(@NonNull Function<? supe
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return concatMapDelayError(mapper, true, 2);
     }
 
@@ -7994,7 +7994,7 @@ public final <R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, ?
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             boolean tillTheEnd, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -8048,7 +8048,7 @@ public final <R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, ?
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             boolean tillTheEnd, int prefetch, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -8081,7 +8081,7 @@ public final <R> Flowable<R> concatMapDelayError(@NonNull Function<? super T, ?
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapEager(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapEager(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return concatMapEager(mapper, bufferSize(), bufferSize());
     }
 
@@ -8113,7 +8113,7 @@ public final <R> Flowable<R> concatMapEager(@NonNull Function<? super T, ? exten
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapEager(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> Flowable<R> concatMapEager(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             int maxConcurrency, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -8149,7 +8149,7 @@ public final <R> Flowable<R> concatMapEager(@NonNull Function<? super T, ? exten
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapEagerDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> Flowable<R> concatMapEagerDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             boolean tillTheEnd) {
         return concatMapEagerDelayError(mapper, tillTheEnd, bufferSize(), bufferSize());
     }
@@ -8187,7 +8187,7 @@ public final <R> Flowable<R> concatMapEagerDelayError(@NonNull Function<? super
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapEagerDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> Flowable<R> concatMapEagerDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             boolean tillTheEnd, int maxConcurrency, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -8221,7 +8221,7 @@ public final <R> Flowable<R> concatMapEagerDelayError(@NonNull Function<? super
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Flowable<U> concatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Flowable<U> concatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         return concatMapIterable(mapper, 2);
     }
 
@@ -8254,7 +8254,7 @@ public final <U> Flowable<U> concatMapIterable(@NonNull Function<? super T, ? ex
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<U> concatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper, int prefetch) {
+    public final <@NonNull U> Flowable<U> concatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableFlattenIterable<>(this, mapper, prefetch));
@@ -8289,7 +8289,7 @@ public final <U> Flowable<U> concatMapIterable(@NonNull Function<? super T, ? ex
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return concatMapMaybe(mapper, 2);
     }
 
@@ -8327,7 +8327,7 @@ public final <R> Flowable<R> concatMapMaybe(@NonNull Function<? super T, ? exten
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, int prefetch) {
+    public final <@NonNull R> Flowable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableConcatMapMaybe<>(this, mapper, ErrorMode.IMMEDIATE, prefetch));
@@ -8362,7 +8362,7 @@ public final <R> Flowable<R> concatMapMaybe(@NonNull Function<? super T, ? exten
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return concatMapMaybeDelayError(mapper, true, 2);
     }
 
@@ -8401,7 +8401,7 @@ public final <R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd) {
+    public final <@NonNull R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd) {
         return concatMapMaybeDelayError(mapper, tillTheEnd, 2);
     }
 
@@ -8444,7 +8444,7 @@ public final <R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd, int prefetch) {
+    public final <@NonNull R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableConcatMapMaybe<>(this, mapper, tillTheEnd ? ErrorMode.END : ErrorMode.BOUNDARY, prefetch));
@@ -8479,7 +8479,7 @@ public final <R> Flowable<R> concatMapMaybeDelayError(@NonNull Function<? super
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return concatMapSingle(mapper, 2);
     }
 
@@ -8517,7 +8517,7 @@ public final <R> Flowable<R> concatMapSingle(@NonNull Function<? super T, ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, int prefetch) {
+    public final <@NonNull R> Flowable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableConcatMapSingle<>(this, mapper, ErrorMode.IMMEDIATE, prefetch));
@@ -8552,7 +8552,7 @@ public final <R> Flowable<R> concatMapSingle(@NonNull Function<? super T, ? exte
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return concatMapSingleDelayError(mapper, true, 2);
     }
 
@@ -8591,7 +8591,7 @@ public final <R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd) {
+    public final <@NonNull R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd) {
         return concatMapSingleDelayError(mapper, tillTheEnd, 2);
     }
 
@@ -8634,7 +8634,7 @@ public final <R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd, int prefetch) {
+    public final <@NonNull R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableConcatMapSingle<>(this, mapper, tillTheEnd ? ErrorMode.END : ErrorMode.BOUNDARY, prefetch));
@@ -8664,7 +8664,7 @@ public final <R> Flowable<R> concatMapSingleDelayError(@NonNull Function<? super
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> concatWith(@NonNull Publisher<@NonNull ? extends T> other) {
+    public final Flowable<T> concatWith(@NonNull Publisher<? extends T> other) {
         Objects.requireNonNull(other, "other is null");
         return concat(this, other);
     }
@@ -8838,7 +8838,7 @@ public final Single<Long> count() {
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> debounce(@NonNull Function<? super T, ? extends Publisher<U>> debounceIndicator) {
+    public final <@NonNull U> Flowable<T> debounce(@NonNull Function<? super T, @NonNull ? extends Publisher<U>> debounceIndicator) {
         Objects.requireNonNull(debounceIndicator, "debounceIndicator is null");
         return RxJavaPlugins.onAssembly(new FlowableDebounce<>(this, debounceIndicator));
     }
@@ -8994,7 +8994,7 @@ public final Flowable<T> defaultIfEmpty(@NonNull T defaultItem) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> delay(@NonNull Function<? super T, ? extends Publisher<U>> itemDelayIndicator) {
+    public final <@NonNull U> Flowable<T> delay(@NonNull Function<? super T, @NonNull ? extends Publisher<U>> itemDelayIndicator) {
         Objects.requireNonNull(itemDelayIndicator, "itemDelayIndicator is null");
         return flatMap(FlowableInternalHelper.itemDelay(itemDelayIndicator));
     }
@@ -9160,8 +9160,8 @@ public final Flowable<T> delay(long time, @NonNull TimeUnit unit, @NonNull Sched
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Flowable<T> delay(@NonNull Publisher<U> subscriptionIndicator,
-            @NonNull Function<? super T, ? extends Publisher<V>> itemDelayIndicator) {
+    public final <@NonNull U, @NonNull V> Flowable<T> delay(@NonNull Publisher<U> subscriptionIndicator,
+            @NonNull Function<? super T, @NonNull ? extends Publisher<V>> itemDelayIndicator) {
         return delaySubscription(subscriptionIndicator).delay(itemDelayIndicator);
     }
 
@@ -9187,7 +9187,7 @@ public final <U, V> Flowable<T> delay(@NonNull Publisher<U> subscriptionIndicato
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> delaySubscription(@NonNull Publisher<U> subscriptionIndicator) {
+    public final <@NonNull U> Flowable<T> delaySubscription(@NonNull Publisher<U> subscriptionIndicator) {
         Objects.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
         return RxJavaPlugins.onAssembly(new FlowableDelaySubscriptionOther<>(this, subscriptionIndicator));
     }
@@ -9303,7 +9303,7 @@ public final Flowable<T> delaySubscription(long time, @NonNull TimeUnit unit, @N
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> Flowable<R> dematerialize(@NonNull Function<@NonNull ? super T, @NonNull Notification<R>> selector) {
+    public final <@NonNull R> Flowable<R> dematerialize(@NonNull Function<@NonNull ? super T, @NonNull Notification<R>> selector) {
         Objects.requireNonNull(selector, "selector is null");
         return RxJavaPlugins.onAssembly(new FlowableDematerialize<>(this, selector));
     }
@@ -9390,7 +9390,7 @@ public final Flowable<T> distinct() {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Flowable<T> distinct(@NonNull Function<? super T, K> keySelector) {
+    public final <@NonNull K> Flowable<T> distinct(@NonNull Function<? super T, K> keySelector) {
         return distinct(keySelector, Functions.createHashSet());
     }
 
@@ -9426,7 +9426,7 @@ public final <K> Flowable<T> distinct(@NonNull Function<? super T, K> keySelecto
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Flowable<T> distinct(@NonNull Function<? super T, K> keySelector,
+    public final <@NonNull K> Flowable<T> distinct(@NonNull Function<? super T, K> keySelector,
             @NonNull Supplier<? extends Collection<? super K>> collectionSupplier) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         Objects.requireNonNull(collectionSupplier, "collectionSupplier is null");
@@ -9517,7 +9517,7 @@ public final Flowable<T> distinctUntilChanged() {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Flowable<T> distinctUntilChanged(@NonNull Function<? super T, K> keySelector) {
+    public final <@NonNull K> Flowable<T> distinctUntilChanged(@NonNull Function<? super T, K> keySelector) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         return RxJavaPlugins.onAssembly(new FlowableDistinctUntilChanged<>(this, keySelector, ObjectHelper.equalsPredicate()));
     }
@@ -9806,7 +9806,7 @@ public final Flowable<T> doOnEach(@NonNull Consumer<@NonNull ? super Notificatio
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> doOnEach(@NonNull Subscriber<@NonNull ? super T> subscriber) {
+    public final Flowable<T> doOnEach(@NonNull Subscriber<? super T> subscriber) {
         Objects.requireNonNull(subscriber, "subscriber is null");
         return doOnEach(
                 FlowableInternalHelper.subscriberOnNext(subscriber),
@@ -10221,7 +10221,7 @@ public final Single<T> firstOrError() {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return flatMap(mapper, false, bufferSize(), bufferSize());
     }
 
@@ -10256,7 +10256,7 @@ public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publ
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, boolean delayErrors) {
+    public final <@NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, boolean delayErrors) {
         return flatMap(mapper, delayErrors, bufferSize(), bufferSize());
     }
 
@@ -10293,7 +10293,7 @@ public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publ
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, int maxConcurrency) {
+    public final <@NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, int maxConcurrency) {
         return flatMap(mapper, false, maxConcurrency, bufferSize());
     }
 
@@ -10333,7 +10333,7 @@ public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publ
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
+    public final <@NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
         return flatMap(mapper, delayErrors, maxConcurrency, bufferSize());
     }
 
@@ -10375,7 +10375,7 @@ public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publ
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             boolean delayErrors, int maxConcurrency, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -10424,10 +10424,10 @@ public final <R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publ
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> onNextMapper,
-            @NonNull Function<? super Throwable, ? extends Publisher<@NonNull ? extends R>> onErrorMapper,
-            @NonNull Supplier<? extends Publisher<@NonNull ? extends R>> onCompleteSupplier) {
+    public final <@NonNull R> Flowable<R> flatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> onNextMapper,
+            @NonNull Function<? super Throwable, @NonNull ? extends Publisher<? extends R>> onErrorMapper,
+            @NonNull Supplier<? extends Publisher<? extends R>> onCompleteSupplier) {
         Objects.requireNonNull(onNextMapper, "onNextMapper is null");
         Objects.requireNonNull(onErrorMapper, "onErrorMapper is null");
         Objects.requireNonNull(onCompleteSupplier, "onCompleteSupplier is null");
@@ -10472,10 +10472,10 @@ public final <R> Flowable<R> flatMap(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> onNextMapper,
-            @NonNull Function<Throwable, ? extends Publisher<@NonNull ? extends R>> onErrorMapper,
-            @NonNull Supplier<? extends Publisher<@NonNull ? extends R>> onCompleteSupplier,
+    public final <@NonNull R> Flowable<R> flatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> onNextMapper,
+            @NonNull Function<Throwable, @NonNull ? extends Publisher<? extends R>> onErrorMapper,
+            @NonNull Supplier<? extends Publisher<? extends R>> onCompleteSupplier,
             int maxConcurrency) {
         Objects.requireNonNull(onNextMapper, "onNextMapper is null");
         Objects.requireNonNull(onErrorMapper, "onErrorMapper is null");
@@ -10516,7 +10516,7 @@ public final <R> Flowable<R> flatMap(
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
         return flatMap(mapper, combiner, false, bufferSize(), bufferSize());
     }
@@ -10556,7 +10556,7 @@ public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends P
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors) {
         return flatMap(mapper, combiner, delayErrors, bufferSize(), bufferSize());
     }
@@ -10601,7 +10601,7 @@ public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends P
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors, int maxConcurrency) {
         return flatMap(mapper, combiner, delayErrors, maxConcurrency, bufferSize());
     }
@@ -10648,7 +10648,7 @@ public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends P
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors, int maxConcurrency, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -10694,7 +10694,7 @@ public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends P
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Flowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Flowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, int maxConcurrency) {
         return flatMap(mapper, combiner, false, maxConcurrency, bufferSize());
     }
@@ -10776,7 +10776,7 @@ public final Completable flatMapCompletable(@NonNull Function<? super T, ? exten
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Flowable<U> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Flowable<U> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         return flatMapIterable(mapper, bufferSize());
     }
 
@@ -10810,7 +10810,7 @@ public final <U> Flowable<U> flatMapIterable(@NonNull Function<? super T, ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<U> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper, int bufferSize) {
+    public final <@NonNull U> Flowable<U> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new FlowableFlattenIterable<>(this, mapper, bufferSize));
@@ -10849,7 +10849,7 @@ public final <U> Flowable<U> flatMapIterable(@NonNull Function<? super T, ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, V> Flowable<V> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull V> Flowable<V> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends V> combiner) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -10894,7 +10894,7 @@ public final <U, V> Flowable<V> flatMapIterable(@NonNull Function<? super T, ? e
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, V> Flowable<V> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull V> Flowable<V> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends V> combiner, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -10919,7 +10919,7 @@ public final <U, V> Flowable<V> flatMapIterable(@NonNull Function<? super T, ? e
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return flatMapMaybe(mapper, false, Integer.MAX_VALUE);
     }
 
@@ -10948,7 +10948,7 @@ public final <R> Flowable<R> flatMapMaybe(@NonNull Function<? super T, ? extends
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
+    public final <@NonNull R> Flowable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapMaybe<>(this, mapper, delayErrors, maxConcurrency));
@@ -10972,7 +10972,7 @@ public final <R> Flowable<R> flatMapMaybe(@NonNull Function<? super T, ? extends
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return flatMapSingle(mapper, false, Integer.MAX_VALUE);
     }
 
@@ -11001,7 +11001,7 @@ public final <R> Flowable<R> flatMapSingle(@NonNull Function<? super T, ? extend
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
+    public final <@NonNull R> Flowable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapSingle<>(this, mapper, delayErrors, maxConcurrency));
@@ -11187,7 +11187,7 @@ public final Disposable forEachWhile(@NonNull Predicate<? super T> onNext, @NonN
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Flowable<GroupedFlowable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector) {
+    public final <@NonNull K> Flowable<GroupedFlowable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector) {
         return groupBy(keySelector, Functions.identity(), false, bufferSize());
     }
 
@@ -11246,7 +11246,7 @@ public final <K> Flowable<GroupedFlowable<K, T>> groupBy(@NonNull Function<? sup
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Flowable<GroupedFlowable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector, boolean delayError) {
+    public final <@NonNull K> Flowable<GroupedFlowable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector, boolean delayError) {
         return groupBy(keySelector, Functions.identity(), delayError, bufferSize());
     }
 
@@ -11309,7 +11309,7 @@ public final <K> Flowable<GroupedFlowable<K, T>> groupBy(@NonNull Function<? sup
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector) {
         return groupBy(keySelector, valueSelector, false, bufferSize());
     }
@@ -11374,7 +11374,7 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<?
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector, boolean delayError) {
         return groupBy(keySelector, valueSelector, delayError, bufferSize());
     }
@@ -11441,7 +11441,7 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<?
     @NonNull
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             boolean delayError, int bufferSize) {
         Objects.requireNonNull(keySelector, "keySelector is null");
@@ -11562,7 +11562,7 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<?
     @NonNull
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             boolean delayError, int bufferSize,
             @NonNull Function<? super Consumer<Object>, ? extends Map<K, Object>> evictingMapFactory) {
@@ -11612,10 +11612,10 @@ public final <K, V> Flowable<GroupedFlowable<K, V>> groupBy(@NonNull Function<?
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <TRight, TLeftEnd, TRightEnd, R> Flowable<R> groupJoin(
-            @NonNull Publisher<@NonNull ? extends TRight> other,
-            @NonNull Function<? super T, ? extends Publisher<@NonNull TLeftEnd>> leftEnd,
-            @NonNull Function<? super TRight, ? extends Publisher<@NonNull TRightEnd>> rightEnd,
+    public final <@NonNull TRight, @NonNull TLeftEnd, @NonNull TRightEnd, @NonNull R> Flowable<R> groupJoin(
+            @NonNull Publisher<? extends TRight> other,
+            @NonNull Function<? super T, @NonNull ? extends Publisher<TLeftEnd>> leftEnd,
+            @NonNull Function<? super TRight, @NonNull ? extends Publisher<TRightEnd>> rightEnd,
             @NonNull BiFunction<? super T, ? super Flowable<TRight>, ? extends R> resultSelector) {
         Objects.requireNonNull(other, "other is null");
         Objects.requireNonNull(leftEnd, "leftEnd is null");
@@ -11736,10 +11736,10 @@ public final Single<Boolean> isEmpty() {
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <TRight, TLeftEnd, TRightEnd, R> Flowable<R> join(
-            @NonNull Publisher<@NonNull ? extends TRight> other,
-            @NonNull Function<? super T, ? extends Publisher<@NonNull TLeftEnd>> leftEnd,
-            @NonNull Function<? super TRight, ? extends Publisher<@NonNull TRightEnd>> rightEnd,
+    public final <@NonNull TRight, @NonNull TLeftEnd, @NonNull TRightEnd, @NonNull R> Flowable<R> join(
+            @NonNull Publisher<? extends TRight> other,
+            @NonNull Function<? super T, @NonNull ? extends Publisher<TLeftEnd>> leftEnd,
+            @NonNull Function<? super TRight, @NonNull ? extends Publisher<TRightEnd>> rightEnd,
             @NonNull BiFunction<? super T, ? super TRight, ? extends R> resultSelector) {
         Objects.requireNonNull(other, "other is null");
         Objects.requireNonNull(leftEnd, "leftEnd is null");
@@ -11976,7 +11976,7 @@ public final Single<T> lastOrError() {
     @NonNull
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> lift(@NonNull FlowableOperator<? extends R, ? super T> lifter) {
+    public final <@NonNull R> Flowable<R> lift(@NonNull FlowableOperator<? extends R, ? super T> lifter) {
         Objects.requireNonNull(lifter, "lifter is null");
         return RxJavaPlugins.onAssembly(new FlowableLift<>(this, lifter));
     }
@@ -12061,7 +12061,7 @@ public final Flowable<Notification<T>> materialize() {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> mergeWith(@NonNull Publisher<@NonNull ? extends T> other) {
+    public final Flowable<T> mergeWith(@NonNull Publisher<? extends T> other) {
         Objects.requireNonNull(other, "other is null");
         return merge(this, other);
     }
@@ -12334,7 +12334,7 @@ public final Flowable<T> observeOn(@NonNull Scheduler scheduler, boolean delayEr
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<U> ofType(@NonNull Class<U> clazz) {
+    public final <@NonNull U> Flowable<U> ofType(@NonNull Class<U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return filter(Functions.isInstanceOf(clazz)).cast(clazz);
     }
@@ -12781,7 +12781,7 @@ public final Flowable<T> onBackpressureReduce(@NonNull BiFunction<T, T, T> reduc
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> onBackpressureReduce(@NonNull Supplier<R> supplier, @NonNull BiFunction<R, ? super T, R> reducer) {
+    public final <@NonNull R> Flowable<R> onBackpressureReduce(@NonNull Supplier<R> supplier, @NonNull BiFunction<R, ? super T, R> reducer) {
         Objects.requireNonNull(supplier, "supplier is null");
         Objects.requireNonNull(reducer, "reducer is null");
         return RxJavaPlugins.onAssembly(new FlowableOnBackpressureReduceWith<>(this, supplier, reducer));
@@ -12878,7 +12878,7 @@ public final Flowable<T> onErrorComplete(@NonNull Predicate<? super Throwable> p
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> onErrorResumeNext(@NonNull Function<? super Throwable, ? extends Publisher<@NonNull ? extends T>> fallbackSupplier) {
+    public final Flowable<T> onErrorResumeNext(@NonNull Function<? super Throwable, @NonNull ? extends Publisher<? extends T>> fallbackSupplier) {
         Objects.requireNonNull(fallbackSupplier, "fallbackSupplier is null");
         return RxJavaPlugins.onAssembly(new FlowableOnErrorNext<>(this, fallbackSupplier));
     }
@@ -12923,7 +12923,7 @@ public final Flowable<T> onErrorResumeNext(@NonNull Function<? super Throwable,
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> onErrorResumeWith(@NonNull Publisher<@NonNull ? extends T> fallback) {
+    public final Flowable<T> onErrorResumeWith(@NonNull Publisher<? extends T> fallback) {
         Objects.requireNonNull(fallback, "fallback is null");
         return onErrorResumeNext(Functions.justFunction(fallback));
     }
@@ -13183,7 +13183,7 @@ public final ConnectableFlowable<T> publish() {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> publish(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector) {
+    public final <@NonNull R> Flowable<R> publish(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector) {
         return publish(selector, bufferSize());
     }
 
@@ -13220,7 +13220,7 @@ public final <R> Flowable<R> publish(@NonNull Function<? super Flowable<T>, ? ex
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> publish(@NonNull Function<? super Flowable<T>, ? extends Publisher<@NonNull ? extends R>> selector, int prefetch) {
+    public final <@NonNull R> Flowable<R> publish(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<? extends R>> selector, int prefetch) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowablePublishMulticast<>(this, selector, prefetch, false));
@@ -13546,7 +13546,7 @@ public final Flowable<T> repeatUntil(@NonNull BooleanSupplier stop) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> repeatWhen(@NonNull Function<? super Flowable<Object>, ? extends Publisher<@NonNull ?>> handler) {
+    public final Flowable<T> repeatWhen(@NonNull Function<? super Flowable<Object>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         Objects.requireNonNull(handler, "handler is null");
         return RxJavaPlugins.onAssembly(new FlowableRepeatWhen<>(this, handler));
     }
@@ -13605,7 +13605,7 @@ public final ConnectableFlowable<T> replay() {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector) {
         Objects.requireNonNull(selector, "selector is null");
         return FlowableReplay.multicastSelector(FlowableInternalHelper.replaySupplier(this), selector);
     }
@@ -13645,7 +13645,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, int bufferSize) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, int bufferSize) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return FlowableReplay.multicastSelector(FlowableInternalHelper.replaySupplier(this, bufferSize, false), selector);
@@ -13688,7 +13688,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, int bufferSize, boolean eagerTruncate) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, int bufferSize, boolean eagerTruncate) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return FlowableReplay.multicastSelector(FlowableInternalHelper.replaySupplier(this, bufferSize, eagerTruncate), selector);
@@ -13732,7 +13732,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     @NonNull
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit) {
         return replay(selector, bufferSize, time, unit, Schedulers.computation());
     }
 
@@ -13778,7 +13778,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(selector, "selector is null");
         Objects.requireNonNull(unit, "unit is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -13831,7 +13831,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
         Objects.requireNonNull(selector, "selector is null");
         Objects.requireNonNull(unit, "unit is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -13872,7 +13872,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     @NonNull
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, long time, @NonNull TimeUnit unit) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, long time, @NonNull TimeUnit unit) {
         return replay(selector, time, unit, Schedulers.computation());
     }
 
@@ -13911,7 +13911,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(selector, "selector is null");
         Objects.requireNonNull(unit, "unit is null");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -13955,7 +13955,7 @@ public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? ext
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final <R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, ? extends Publisher<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
+    public final <@NonNull R> Flowable<R> replay(@NonNull Function<? super Flowable<T>, @NonNull ? extends Publisher<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
         Objects.requireNonNull(selector, "selector is null");
         Objects.requireNonNull(unit, "unit is null");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -14544,7 +14544,7 @@ public final Flowable<T> retryUntil(@NonNull BooleanSupplier stop) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     public final Flowable<T> retryWhen(
-            @NonNull Function<? super Flowable<Throwable>, ? extends Publisher<@NonNull ?>> handler) {
+            @NonNull Function<? super Flowable<Throwable>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         Objects.requireNonNull(handler, "handler is null");
 
         return RxJavaPlugins.onAssembly(new FlowableRetryWhen<>(this, handler));
@@ -14566,10 +14566,10 @@ public final Flowable<T> retryWhen(
      */
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final void safeSubscribe(@NonNull Subscriber<@NonNull ? super T> subscriber) {
+    public final void safeSubscribe(@NonNull Subscriber<? super T> subscriber) {
         Objects.requireNonNull(subscriber, "subscriber is null");
         if (subscriber instanceof SafeSubscriber) {
-            subscribe((SafeSubscriber<@NonNull ? super T>)subscriber);
+            subscribe((SafeSubscriber<? super T>)subscriber);
         } else {
             subscribe(new SafeSubscriber<>(subscriber));
         }
@@ -14742,7 +14742,7 @@ public final Flowable<T> sample(long period, @NonNull TimeUnit unit, @NonNull Sc
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> sample(@NonNull Publisher<U> sampler) {
+    public final <@NonNull U> Flowable<T> sample(@NonNull Publisher<U> sampler) {
         Objects.requireNonNull(sampler, "sampler is null");
         return RxJavaPlugins.onAssembly(new FlowableSamplePublisher<>(this, sampler, false));
     }
@@ -14780,7 +14780,7 @@ public final <U> Flowable<T> sample(@NonNull Publisher<U> sampler) {
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> sample(@NonNull Publisher<U> sampler, boolean emitLast) {
+    public final <@NonNull U> Flowable<T> sample(@NonNull Publisher<U> sampler, boolean emitLast) {
         Objects.requireNonNull(sampler, "sampler is null");
         return RxJavaPlugins.onAssembly(new FlowableSamplePublisher<>(this, sampler, emitLast));
     }
@@ -15390,7 +15390,7 @@ public final Flowable<T> skipLast(long time, @NonNull TimeUnit unit, @NonNull Sc
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> skipUntil(@NonNull Publisher<U> other) {
+    public final <@NonNull U> Flowable<T> skipUntil(@NonNull Publisher<U> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new FlowableSkipUntil<>(this, other));
     }
@@ -15508,7 +15508,7 @@ public final Flowable<T> sorted(@NonNull Comparator<@NonNull ? super T> comparat
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Flowable<T> startWithIterable(@NonNull Iterable<@NonNull ? extends T> items) {
+    public final Flowable<T> startWithIterable(@NonNull Iterable<? extends T> items) {
         return concatArray(fromIterable(items), this);
     }
 
@@ -15611,7 +15611,7 @@ public final Flowable<T> startWith(@NonNull MaybeSource<T> other) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> startWith(@NonNull Publisher<@NonNull ? extends T> other) {
+    public final Flowable<T> startWith(@NonNull Publisher<? extends T> other) {
         Objects.requireNonNull(other, "other is null");
         return concatArray(other, this);
     }
@@ -15858,9 +15858,9 @@ public final Disposable subscribe(
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @Override
-    public final void subscribe(@NonNull Subscriber<@NonNull ? super T> subscriber) {
+    public final void subscribe(@NonNull Subscriber<? super T> subscriber) {
         if (subscriber instanceof FlowableSubscriber) {
-            subscribe((FlowableSubscriber<@NonNull ? super T>)subscriber);
+            subscribe((FlowableSubscriber<? super T>)subscriber);
         } else {
             Objects.requireNonNull(subscriber, "subscriber is null");
             subscribe(new StrictSubscriber<>(subscriber));
@@ -15907,10 +15907,10 @@ public final void subscribe(@NonNull Subscriber<@NonNull ? super T> subscriber)
      */
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final void subscribe(@NonNull FlowableSubscriber<@NonNull ? super T> subscriber) {
+    public final void subscribe(@NonNull FlowableSubscriber<? super T> subscriber) {
         Objects.requireNonNull(subscriber, "subscriber is null");
         try {
-            Subscriber<@NonNull ? super T> flowableSubscriber = RxJavaPlugins.onSubscribe(this, subscriber);
+            Subscriber<? super T> flowableSubscriber = RxJavaPlugins.onSubscribe(this, subscriber);
 
             Objects.requireNonNull(flowableSubscriber, "The RxJavaPlugins.onSubscribe hook returned a null FlowableSubscriber. Please check the handler provided to RxJavaPlugins.setOnFlowableSubscribe for invalid null returns. Further reading: https://github.com/ReactiveX/RxJava/wiki/Plugins");
 
@@ -15937,7 +15937,7 @@ public final void subscribe(@NonNull FlowableSubscriber<@NonNull ? super T> subs
      * applied by {@link #subscribe(Subscriber)} before this method gets called.
      * @param subscriber the incoming {@code Subscriber}, never {@code null}
      */
-    protected abstract void subscribeActual(@NonNull Subscriber<@NonNull ? super T> subscriber);
+    protected abstract void subscribeActual(@NonNull Subscriber<? super T> subscriber);
 
     /**
      * Subscribes a given {@link Subscriber} (subclass) to this {@code Flowable} and returns the given
@@ -15970,7 +15970,7 @@ public final void subscribe(@NonNull FlowableSubscriber<@NonNull ? super T> subs
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull E extends Subscriber<@NonNull ? super T>> E subscribeWith(E subscriber) {
+    public final <@NonNull E extends Subscriber<? super T>> E subscribeWith(E subscriber) {
         subscribe(subscriber);
         return subscriber;
     }
@@ -16073,7 +16073,7 @@ public final Flowable<T> subscribeOn(@NonNull Scheduler scheduler, boolean reque
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final Flowable<T> switchIfEmpty(@NonNull Publisher<@NonNull ? extends T> other) {
+    public final Flowable<T> switchIfEmpty(@NonNull Publisher<? extends T> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchIfEmpty<>(this, other));
     }
@@ -16110,7 +16110,7 @@ public final Flowable<T> switchIfEmpty(@NonNull Publisher<@NonNull ? extends T>
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> switchMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> switchMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return switchMap(mapper, bufferSize());
     }
 
@@ -16149,7 +16149,7 @@ public final <R> Flowable<R> switchMap(@NonNull Function<? super T, ? extends Pu
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> switchMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Flowable<R> switchMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, int bufferSize) {
         return switchMap0(mapper, bufferSize, false);
     }
 
@@ -16282,7 +16282,7 @@ public final Completable switchMapCompletableDelayError(@NonNull Function<? supe
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> switchMapDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> switchMapDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return switchMapDelayError(mapper, bufferSize());
     }
 
@@ -16323,11 +16323,11 @@ public final <R> Flowable<R> switchMapDelayError(@NonNull Function<? super T, ?
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Flowable<R> switchMapDelayError(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Flowable<R> switchMapDelayError(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, int bufferSize) {
         return switchMap0(mapper, bufferSize, true);
     }
 
-    <R> Flowable<R> switchMap0(Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, int bufferSize, boolean delayError) {
+    <R> Flowable<R> switchMap0(Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, int bufferSize, boolean delayError) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         if (this instanceof ScalarSupplier) {
@@ -16378,7 +16378,7 @@ <R> Flowable<R> switchMap0(Function<? super T, ? extends Publisher<@NonNull ? ex
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> switchMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> switchMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapMaybe<>(this, mapper, false));
     }
@@ -16410,7 +16410,7 @@ public final <R> Flowable<R> switchMapMaybe(@NonNull Function<? super T, ? exten
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> switchMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> switchMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapMaybe<>(this, mapper, true));
     }
@@ -16452,7 +16452,7 @@ public final <R> Flowable<R> switchMapMaybeDelayError(@NonNull Function<? super
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> switchMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> switchMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapSingle<>(this, mapper, false));
     }
@@ -16484,7 +16484,7 @@ public final <R> Flowable<R> switchMapSingle(@NonNull Function<? super T, ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> switchMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> switchMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapSingle<>(this, mapper, true));
     }
@@ -16996,7 +16996,7 @@ public final Flowable<T> takeUntil(@NonNull Predicate<? super T> stopPredicate)
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<T> takeUntil(@NonNull Publisher<U> other) {
+    public final <@NonNull U> Flowable<T> takeUntil(@NonNull Publisher<U> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new FlowableTakeUntil<>(this, other));
     }
@@ -17548,7 +17548,7 @@ public final Flowable<Timed<T>> timeInterval(@NonNull TimeUnit unit, @NonNull Sc
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <V> Flowable<T> timeout(@NonNull Function<? super T, ? extends Publisher<V>> itemTimeoutIndicator) {
+    public final <@NonNull V> Flowable<T> timeout(@NonNull Function<? super T, @NonNull ? extends Publisher<V>> itemTimeoutIndicator) {
         return timeout0(null, itemTimeoutIndicator, null);
     }
 
@@ -17586,7 +17586,7 @@ public final <V> Flowable<T> timeout(@NonNull Function<? super T, ? extends Publ
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <V> Flowable<T> timeout(@NonNull Function<? super T, ? extends Publisher<@NonNull V>> itemTimeoutIndicator, @NonNull Publisher<@NonNull ? extends T> fallback) {
+    public final <@NonNull V> Flowable<T> timeout(@NonNull Function<? super T, @NonNull ? extends Publisher<V>> itemTimeoutIndicator, @NonNull Publisher<? extends T> fallback) {
         Objects.requireNonNull(fallback, "fallback is null");
         return timeout0(null, itemTimeoutIndicator, fallback);
     }
@@ -17651,7 +17651,7 @@ public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit) {
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
-    public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull Publisher<@NonNull ? extends T> fallback) {
+    public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull Publisher<? extends T> fallback) {
         Objects.requireNonNull(fallback, "fallback is null");
         return timeout0(timeout, unit, fallback, Schedulers.computation());
     }
@@ -17689,7 +17689,7 @@ public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.CUSTOM)
-    public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, @NonNull Publisher<@NonNull ? extends T> fallback) {
+    public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, @NonNull Publisher<? extends T> fallback) {
         Objects.requireNonNull(fallback, "fallback is null");
         return timeout0(timeout, unit, fallback, scheduler);
     }
@@ -17761,8 +17761,8 @@ public final Flowable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, V> Flowable<T> timeout(@NonNull Publisher<U> firstTimeoutIndicator,
-            @NonNull Function<? super T, ? extends Publisher<V>> itemTimeoutIndicator) {
+    public final <@NonNull U, @NonNull V> Flowable<T> timeout(@NonNull Publisher<U> firstTimeoutIndicator,
+            @NonNull Function<? super T, @NonNull ? extends Publisher<V>> itemTimeoutIndicator) {
         Objects.requireNonNull(firstTimeoutIndicator, "firstTimeoutIndicator is null");
         return timeout0(firstTimeoutIndicator, itemTimeoutIndicator, null);
     }
@@ -17804,26 +17804,26 @@ public final <U, V> Flowable<T> timeout(@NonNull Publisher<U> firstTimeoutIndica
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, V> Flowable<T> timeout(
+    public final <@NonNull U, @NonNull V> Flowable<T> timeout(
             @NonNull Publisher<U> firstTimeoutIndicator,
-            @NonNull Function<? super T, ? extends Publisher<V>> itemTimeoutIndicator,
-            @NonNull Publisher<@NonNull ? extends T> fallback) {
+            @NonNull Function<? super T, @NonNull ? extends Publisher<V>> itemTimeoutIndicator,
+            @NonNull Publisher<? extends T> fallback) {
         Objects.requireNonNull(firstTimeoutIndicator, "firstTimeoutIndicator is null");
         Objects.requireNonNull(fallback, "fallback is null");
         return timeout0(firstTimeoutIndicator, itemTimeoutIndicator, fallback);
     }
 
-    private Flowable<T> timeout0(long timeout, TimeUnit unit, Publisher<@NonNull ? extends T> fallback,
+    private Flowable<T> timeout0(long timeout, TimeUnit unit, Publisher<? extends T> fallback,
             Scheduler scheduler) {
         Objects.requireNonNull(unit, "unit is null");
         Objects.requireNonNull(scheduler, "scheduler is null");
         return RxJavaPlugins.onAssembly(new FlowableTimeoutTimed<>(this, timeout, unit, scheduler, fallback));
     }
 
-    private <U, V> Flowable<T> timeout0(
+    private <@NonNull U, @NonNull V> Flowable<T> timeout0(
             Publisher<U> firstTimeoutIndicator,
-            Function<? super T, ? extends Publisher<@NonNull V>> itemTimeoutIndicator,
-                    Publisher<@NonNull ? extends T> fallback) {
+            Function<? super T, @NonNull ? extends Publisher<V>> itemTimeoutIndicator,
+                    Publisher<? extends T> fallback) {
         Objects.requireNonNull(itemTimeoutIndicator, "itemTimeoutIndicator is null");
         return RxJavaPlugins.onAssembly(new FlowableTimeout<>(this, firstTimeoutIndicator, itemTimeoutIndicator, fallback));
     }
@@ -17959,7 +17959,7 @@ public final Flowable<Timed<T>> timestamp(@NonNull TimeUnit unit, @NonNull Sched
     @CheckReturnValue
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> R to(@NonNull FlowableConverter<T, ? extends R> converter) {
+    public final <@NonNull R> R to(@NonNull FlowableConverter<T, ? extends R> converter) {
         return Objects.requireNonNull(converter, "converter is null").apply(this);
     }
 
@@ -18069,7 +18069,7 @@ public final Single<List<T>> toList(int capacityHint) {
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U extends Collection<? super T>> Single<U> toList(@NonNull Supplier<U> collectionSupplier) {
+    public final <@NonNull U extends Collection<? super T>> Single<U> toList(@NonNull Supplier<U> collectionSupplier) {
         Objects.requireNonNull(collectionSupplier, "collectionSupplier is null");
         return RxJavaPlugins.onAssembly(new FlowableToListSingle<>(this, collectionSupplier));
     }
@@ -18104,7 +18104,7 @@ public final <U extends Collection<? super T>> Single<U> toList(@NonNull Supplie
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <K> Single<Map<K, T>> toMap(@NonNull Function<? super T, ? extends K> keySelector) {
+    public final <@NonNull K> Single<Map<K, T>> toMap(@NonNull Function<? super T, ? extends K> keySelector) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         return collect(HashMapSupplier.asSupplier(), Functions.toMapKeySelector(keySelector));
     }
@@ -18143,7 +18143,7 @@ public final <K> Single<Map<K, T>> toMap(@NonNull Function<? super T, ? extends
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <K, V> Single<Map<K, V>> toMap(@NonNull Function<? super T, ? extends K> keySelector, @NonNull Function<? super T, ? extends V> valueSelector) {
+    public final <@NonNull K, @NonNull V> Single<Map<K, V>> toMap(@NonNull Function<? super T, ? extends K> keySelector, @NonNull Function<? super T, ? extends V> valueSelector) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         Objects.requireNonNull(valueSelector, "valueSelector is null");
         return collect(HashMapSupplier.asSupplier(), Functions.toMapKeyValueSelector(keySelector, valueSelector));
@@ -18182,7 +18182,7 @@ public final <K, V> Single<Map<K, V>> toMap(@NonNull Function<? super T, ? exten
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <K, V> Single<Map<K, V>> toMap(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Single<Map<K, V>> toMap(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             @NonNull Supplier<? extends Map<K, V>> mapSupplier) {
         Objects.requireNonNull(keySelector, "keySelector is null");
@@ -18217,7 +18217,7 @@ public final <K, V> Single<Map<K, V>> toMap(@NonNull Function<? super T, ? exten
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Single<Map<K, Collection<T>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector) {
+    public final <@NonNull K> Single<Map<K, Collection<T>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector) {
         Function<T, T> valueSelector = Functions.identity();
         Supplier<Map<K, Collection<T>>> mapSupplier = HashMapSupplier.asSupplier();
         Function<K, List<T>> collectionFactory = ArrayListSupplier.asFunction();
@@ -18256,7 +18256,7 @@ public final <K> Single<Map<K, Collection<T>>> toMultimap(@NonNull Function<? su
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<Map<K, Collection<V>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector, @NonNull Function<? super T, ? extends V> valueSelector) {
+    public final <@NonNull K, @NonNull V> Single<Map<K, Collection<V>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector, @NonNull Function<? super T, ? extends V> valueSelector) {
         Supplier<Map<K, Collection<V>>> mapSupplier = HashMapSupplier.asSupplier();
         Function<K, List<V>> collectionFactory = ArrayListSupplier.asFunction();
         return toMultimap(keySelector, valueSelector, mapSupplier, collectionFactory);
@@ -18298,7 +18298,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(@NonNull Function<?
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
+    public final <@NonNull K, @NonNull V> Single<Map<K, Collection<V>>> toMultimap(
             @NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             @NonNull Supplier<? extends Map<K, Collection<V>>> mapSupplier,
@@ -18344,7 +18344,7 @@ public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<Map<K, Collection<V>>> toMultimap(
+    public final <@NonNull K, @NonNull V> Single<Map<K, Collection<V>>> toMultimap(
             @NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             @NonNull Supplier<Map<K, Collection<V>>> mapSupplier
@@ -19143,7 +19143,7 @@ public final Flowable<Flowable<T>> window(
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Flowable<Flowable<T>> window(@NonNull Publisher<B> boundaryIndicator) {
+    public final <@NonNull B> Flowable<Flowable<T>> window(@NonNull Publisher<B> boundaryIndicator) {
         return window(boundaryIndicator, bufferSize());
     }
 
@@ -19181,7 +19181,7 @@ public final <B> Flowable<Flowable<T>> window(@NonNull Publisher<B> boundaryIndi
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <B> Flowable<Flowable<T>> window(@NonNull Publisher<B> boundaryIndicator, int bufferSize) {
+    public final <@NonNull B> Flowable<Flowable<T>> window(@NonNull Publisher<B> boundaryIndicator, int bufferSize) {
         Objects.requireNonNull(boundaryIndicator, "boundaryIndicator is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new FlowableWindowBoundary<>(this, boundaryIndicator, bufferSize));
@@ -19224,9 +19224,9 @@ public final <B> Flowable<Flowable<T>> window(@NonNull Publisher<B> boundaryIndi
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Flowable<Flowable<T>> window(
+    public final <@NonNull U, @NonNull V> Flowable<Flowable<T>> window(
             @NonNull Publisher<U> openingIndicator,
-            @NonNull Function<? super U, ? extends Publisher<V>> closingIndicator) {
+            @NonNull Function<? super U, @NonNull ? extends Publisher<V>> closingIndicator) {
         return window(openingIndicator, closingIndicator, bufferSize());
     }
 
@@ -19270,9 +19270,9 @@ public final <U, V> Flowable<Flowable<T>> window(
     @NonNull
     @BackpressureSupport(BackpressureKind.ERROR)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, V> Flowable<Flowable<T>> window(
+    public final <@NonNull U, @NonNull V> Flowable<Flowable<T>> window(
             @NonNull Publisher<U> openingIndicator,
-            @NonNull Function<? super U, ? extends Publisher<V>> closingIndicator, int bufferSize) {
+            @NonNull Function<? super U, @NonNull ? extends Publisher<V>> closingIndicator, int bufferSize) {
         Objects.requireNonNull(openingIndicator, "openingIndicator is null");
         Objects.requireNonNull(closingIndicator, "closingIndicator is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -19317,7 +19317,7 @@ public final <U, V> Flowable<Flowable<T>> window(
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, @NonNull R> Flowable<R> withLatestFrom(@NonNull Publisher<@NonNull ? extends U> other,
+    public final <@NonNull U, @NonNull R> Flowable<R> withLatestFrom(@NonNull Publisher<? extends U> other,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
         Objects.requireNonNull(other, "other is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -19358,7 +19358,7 @@ public final <U, V> Flowable<Flowable<T>> window(
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T1, T2, @NonNull R> Flowable<R> withLatestFrom(@NonNull Publisher<T1> source1, @NonNull Publisher<T2> source2,
+    public final <@NonNull T1, @NonNull T2, @NonNull R> Flowable<R> withLatestFrom(@NonNull Publisher<T1> source1, @NonNull Publisher<T2> source2,
             @NonNull Function3<? super T, ? super T1, ? super T2, R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -19402,7 +19402,7 @@ public final <U, V> Flowable<Flowable<T>> window(
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T1, T2, T3, @NonNull R> Flowable<R> withLatestFrom(
+    public final <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Flowable<R> withLatestFrom(
             @NonNull Publisher<T1> source1, @NonNull Publisher<T2> source2,
             @NonNull Publisher<T3> source3,
             @NonNull Function4<? super T, ? super T1, ? super T2, ? super T3, R> combiner) {
@@ -19452,7 +19452,7 @@ public final <U, V> Flowable<Flowable<T>> window(
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <T1, T2, T3, T4, @NonNull R> Flowable<R> withLatestFrom(
+    public final <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Flowable<R> withLatestFrom(
             @NonNull Publisher<T1> source1, @NonNull Publisher<T2> source2,
             @NonNull Publisher<T3> source3, @NonNull Publisher<T4> source4,
             @NonNull Function5<? super T, ? super T1, ? super T2, ? super T3, ? super T4, R> combiner) {
@@ -19531,7 +19531,7 @@ public final <U, V> Flowable<Flowable<T>> window(
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> withLatestFrom(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ?>> others, @NonNull Function<? super Object[], R> combiner) {
+    public final <@NonNull R> Flowable<R> withLatestFrom(@NonNull Iterable<@NonNull ? extends Publisher<@NonNull ?>> others, @NonNull Function<? super Object[], R> combiner) {
         Objects.requireNonNull(others, "others is null");
         Objects.requireNonNull(combiner, "combiner is null");
         return RxJavaPlugins.onAssembly(new FlowableWithLatestFromMany<>(this, others, combiner));
@@ -19571,7 +19571,7 @@ public final <R> Flowable<R> withLatestFrom(@NonNull Iterable<@NonNull ? extends
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <@NonNull U, R> Flowable<R> zipWith(@NonNull Iterable<U> other,  @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
+    public final <@NonNull U, @NonNull R> Flowable<R> zipWith(@NonNull Iterable<U> other,  @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
         Objects.requireNonNull(other, "other is null");
         Objects.requireNonNull(zipper, "zipper is null");
         return RxJavaPlugins.onAssembly(new FlowableZipIterable<>(this, other, zipper));
@@ -19620,7 +19620,7 @@ public final <R> Flowable<R> withLatestFrom(@NonNull Iterable<@NonNull ? extends
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, R> Flowable<R> zipWith(@NonNull Publisher<@NonNull ? extends U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
+    public final <@NonNull U, @NonNull R> Flowable<R> zipWith(@NonNull Publisher<? extends U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
         Objects.requireNonNull(other, "other is null");
         return zip(this, other, zipper);
     }
@@ -19671,7 +19671,7 @@ public final <U, R> Flowable<R> zipWith(@NonNull Publisher<@NonNull ? extends U>
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Flowable<R> zipWith(@NonNull Publisher<@NonNull ? extends U> other,
+    public final <@NonNull U, @NonNull R> Flowable<R> zipWith(@NonNull Publisher<? extends U> other,
             @NonNull BiFunction<? super T, ? super U, ? extends R> zipper, boolean delayError) {
         return zip(this, other, zipper, delayError);
     }
@@ -19725,7 +19725,7 @@ public final <U, R> Flowable<R> zipWith(@NonNull Publisher<@NonNull ? extends U>
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Flowable<R> zipWith(@NonNull Publisher<@NonNull ? extends U> other,
+    public final <@NonNull U, @NonNull R> Flowable<R> zipWith(@NonNull Publisher<? extends U> other,
             @NonNull BiFunction<? super T, ? super U, ? extends R> zipper, boolean delayError, int bufferSize) {
         return zip(this, other, zipper, delayError, bufferSize);
     }
@@ -19840,7 +19840,7 @@ public final TestSubscriber<T> test(long initialRequest, boolean cancel) { // No
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<@NonNull T> fromOptional(@NonNull Optional<T> optional) {
+    public static <@NonNull T> Flowable<@NonNull T> fromOptional(@NonNull Optional<T> optional) {
         Objects.requireNonNull(optional, "optional is null");
         return optional.map(Flowable::just).orElseGet(Flowable::empty);
     }
@@ -19878,7 +19878,7 @@ public final TestSubscriber<T> test(long initialRequest, boolean cancel) { // No
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
+    public static <@NonNull T> Flowable<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
         Objects.requireNonNull(stage, "stage is null");
         return RxJavaPlugins.onAssembly(new FlowableFromCompletionStage<>(stage));
     }
@@ -19925,7 +19925,7 @@ public final TestSubscriber<T> test(long initialRequest, boolean cancel) { // No
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<@NonNull T> fromStream(@NonNull Stream<T> stream) {
+    public static <@NonNull T> Flowable<@NonNull T> fromStream(@NonNull Stream<T> stream) {
         Objects.requireNonNull(stream, "stream is null");
         return RxJavaPlugins.onAssembly(new FlowableFromStream<>(stream));
     }
@@ -19986,7 +19986,7 @@ public final TestSubscriber<T> test(long initialRequest, boolean cancel) { // No
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R, A> Single<R> collect(@NonNull Collector<? super T, A, R> collector) {
+    public final <@NonNull R, @NonNull A> Single<R> collect(@NonNull Collector<? super T, A, R> collector) {
         Objects.requireNonNull(collector, "collector is null");
         return RxJavaPlugins.onAssembly(new FlowableCollectWithCollectorSingle<>(this, collector));
     }
@@ -20312,7 +20312,7 @@ public final Stream<T> blockingStream(int prefetch) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> Flowable<R> concatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> concatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         return flatMapStream(mapper, bufferSize());
     }
 
@@ -20367,7 +20367,7 @@ public final Stream<T> blockingStream(int prefetch) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> Flowable<R> concatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<@NonNull ? extends R>> mapper, int prefetch) {
+    public final <@NonNull R> Flowable<R> concatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapStream<>(this, mapper, prefetch));
@@ -20423,7 +20423,7 @@ public final Stream<T> blockingStream(int prefetch) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> Flowable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         return flatMapStream(mapper, bufferSize());
     }
 
@@ -20478,7 +20478,7 @@ public final Stream<T> blockingStream(int prefetch) {
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> Flowable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<@NonNull ? extends R>> mapper, int prefetch) {
+    public final <@NonNull R> Flowable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapStream<>(this, mapper, prefetch));
diff --git a/src/main/java/io/reactivex/rxjava3/core/Maybe.java b/src/main/java/io/reactivex/rxjava3/core/Maybe.java
index 917a9838a4..bbb3a10d4b 100644
--- a/src/main/java/io/reactivex/rxjava3/core/Maybe.java
+++ b/src/main/java/io/reactivex/rxjava3/core/Maybe.java
@@ -130,7 +130,7 @@ public abstract class Maybe<T> implements MaybeSource<T> {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> amb(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Maybe<T> amb(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new MaybeAmb<>(null, sources));
     }
@@ -154,7 +154,7 @@ public static <T> Maybe<T> amb(@NonNull Iterable<@NonNull ? extends MaybeSource<
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Maybe<T> ambArray(@NonNull MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Maybe<T> ambArray(@NonNull MaybeSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -187,7 +187,7 @@ public static <T> Maybe<T> ambArray(@NonNull MaybeSource<? extends T>... sources
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new MaybeConcatIterable<>(sources));
     }
@@ -216,7 +216,7 @@ public static <T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends MaybeS
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return concatArray(source1, source2);
@@ -248,7 +248,7 @@ public static <T> Flowable<T> concat(@NonNull MaybeSource<? extends T> source1,
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
+    public static <@NonNull T> Flowable<T> concat(
             @NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -284,7 +284,7 @@ public static <T> Flowable<T> concat(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
+    public static <@NonNull T> Flowable<T> concat(
             @NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3, @NonNull MaybeSource<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -315,7 +315,7 @@ public static <T> Flowable<T> concat(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return concat(sources, 2);
     }
 
@@ -343,7 +343,7 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Maybe
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int prefetch) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int prefetch) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableConcatMapMaybePublisher<>(sources, Functions.identity(), ErrorMode.IMMEDIATE, prefetch));
@@ -370,7 +370,7 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Maybe
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> concatArray(@NonNull MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArray(@NonNull MaybeSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return Flowable.empty();
@@ -404,7 +404,7 @@ public static <T> Flowable<T> concatArray(@NonNull MaybeSource<? extends T>... s
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> concatArrayDelayError(@NonNull MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayDelayError(@NonNull MaybeSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return Flowable.empty();
@@ -442,7 +442,7 @@ public static <T> Flowable<T> concatArrayDelayError(@NonNull MaybeSource<? exten
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Flowable<T> concatArrayEager(@NonNull MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEager(@NonNull MaybeSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapEager((Function)MaybeToPublisher.instance());
     }
     /**
@@ -471,7 +471,7 @@ public static <T> Flowable<T> concatArrayEager(@NonNull MaybeSource<? extends T>
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Flowable<T> concatArrayEagerDelayError(@NonNull MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEagerDelayError(@NonNull MaybeSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), true);
     }
 
@@ -497,7 +497,7 @@ public static <T> Flowable<T> concatArrayEagerDelayError(@NonNull MaybeSource<?
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapMaybeDelayError(Functions.identity());
     }
 
@@ -523,7 +523,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapMaybeDelayError(Functions.identity());
     }
     /**
@@ -554,7 +554,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int prefetch) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int prefetch) {
         return Flowable.fromPublisher(sources).concatMapMaybeDelayError(Functions.identity(), true, prefetch);
     }
 
@@ -582,7 +582,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), false);
     }
 
@@ -615,7 +615,7 @@ public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends M
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), false, maxConcurrency, 1);
     }
 
@@ -645,7 +645,7 @@ public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends M
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapEager((Function)MaybeToPublisher.instance());
     }
 
@@ -680,7 +680,7 @@ public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromPublisher(sources).concatMapEager((Function)MaybeToPublisher.instance(), maxConcurrency, 1);
     }
 
@@ -710,7 +710,7 @@ public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), true);
     }
 
@@ -744,7 +744,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), true, maxConcurrency, 1);
     }
 
@@ -776,7 +776,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), true);
     }
 
@@ -812,7 +812,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromPublisher(sources).concatMapEagerDelayError((Function)MaybeToPublisher.instance(), true, maxConcurrency, 1);
     }
 
@@ -866,7 +866,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> create(@NonNull MaybeOnSubscribe<T> onSubscribe) {
+    public static <@NonNull T> Maybe<T> create(@NonNull MaybeOnSubscribe<T> onSubscribe) {
         Objects.requireNonNull(onSubscribe, "onSubscribe is null");
         return RxJavaPlugins.onAssembly(new MaybeCreate<>(onSubscribe));
     }
@@ -889,7 +889,7 @@ public static <T> Maybe<T> create(@NonNull MaybeOnSubscribe<T> onSubscribe) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> defer(@NonNull Supplier<? extends MaybeSource<? extends T>> supplier) {
+    public static <@NonNull T> Maybe<T> defer(@NonNull Supplier<? extends MaybeSource<? extends T>> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new MaybeDefer<>(supplier));
     }
@@ -910,7 +910,7 @@ public static <T> Maybe<T> defer(@NonNull Supplier<? extends MaybeSource<? exten
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Maybe<T> empty() {
+    public static <@NonNull T> Maybe<T> empty() {
         return RxJavaPlugins.onAssembly((Maybe<T>)MaybeEmpty.INSTANCE);
     }
 
@@ -935,7 +935,7 @@ public static <T> Maybe<T> empty() {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> error(@NonNull Throwable throwable) {
+    public static <@NonNull T> Maybe<T> error(@NonNull Throwable throwable) {
         Objects.requireNonNull(throwable, "throwable is null");
         return RxJavaPlugins.onAssembly(new MaybeError<>(throwable));
     }
@@ -961,7 +961,7 @@ public static <T> Maybe<T> error(@NonNull Throwable throwable) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> error(@NonNull Supplier<? extends Throwable> supplier) {
+    public static <@NonNull T> Maybe<T> error(@NonNull Supplier<? extends Throwable> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new MaybeErrorCallable<>(supplier));
     }
@@ -990,7 +990,7 @@ public static <T> Maybe<T> error(@NonNull Supplier<? extends Throwable> supplier
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> fromAction(@NonNull Action action) {
+    public static <@NonNull T> Maybe<T> fromAction(@NonNull Action action) {
         Objects.requireNonNull(action, "action is null");
         return RxJavaPlugins.onAssembly(new MaybeFromAction<>(action));
     }
@@ -1011,7 +1011,7 @@ public static <T> Maybe<T> fromAction(@NonNull Action action) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> fromCompletable(@NonNull CompletableSource completableSource) {
+    public static <@NonNull T> Maybe<T> fromCompletable(@NonNull CompletableSource completableSource) {
         Objects.requireNonNull(completableSource, "completableSource is null");
         return RxJavaPlugins.onAssembly(new MaybeFromCompletable<>(completableSource));
     }
@@ -1032,7 +1032,7 @@ public static <T> Maybe<T> fromCompletable(@NonNull CompletableSource completabl
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> fromSingle(@NonNull SingleSource<T> single) {
+    public static <@NonNull T> Maybe<T> fromSingle(@NonNull SingleSource<T> single) {
         Objects.requireNonNull(single, "single is null");
         return RxJavaPlugins.onAssembly(new MaybeFromSingle<>(single));
     }
@@ -1175,7 +1175,7 @@ public static <T> Maybe<T> fromSingle(@NonNull SingleSource<T> single) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> fromObservable(@NonNull ObservableSource<T> source) {
+    public static <@NonNull T> Maybe<T> fromObservable(@NonNull ObservableSource<T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new ObservableElementAtMaybe<>(source, 0L));
     }
@@ -1202,7 +1202,7 @@ public static <T> Maybe<T> fromObservable(@NonNull ObservableSource<T> source) {
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
-    public static <T> Maybe<T> fromPublisher(@NonNull Publisher<T> source) {
+    public static <@NonNull T> Maybe<T> fromPublisher(@NonNull Publisher<T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new FlowableElementAtMaybePublisher<>(source, 0L));
     }
@@ -1237,7 +1237,7 @@ public static <T> Maybe<T> fromPublisher(@NonNull Publisher<T> source) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> fromRunnable(@NonNull Runnable run) {
+    public static <@NonNull T> Maybe<T> fromRunnable(@NonNull Runnable run) {
         Objects.requireNonNull(run, "run is null");
         return RxJavaPlugins.onAssembly(new MaybeFromRunnable<>(run));
     }
@@ -1352,7 +1352,7 @@ public static <T> Maybe<T> fromRunnable(@NonNull Runnable run) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).flatMapMaybe(Functions.identity(), false, Integer.MAX_VALUE);
     }
 
@@ -1390,7 +1390,7 @@ public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends MaybeSo
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return merge(sources, Integer.MAX_VALUE);
     }
 
@@ -1430,7 +1430,7 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends MaybeS
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapMaybePublisher<>(sources, Functions.identity(), false, maxConcurrency));
@@ -1463,7 +1463,7 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends MaybeS
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
-    public static <T> Maybe<T> merge(@NonNull MaybeSource<? extends MaybeSource<? extends T>> source) {
+    public static <@NonNull T> Maybe<T> merge(@NonNull MaybeSource<? extends MaybeSource<? extends T>> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatten(source, Functions.identity()));
     }
@@ -1509,7 +1509,7 @@ public static <T> Maybe<T> merge(@NonNull MaybeSource<? extends MaybeSource<? ex
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
+    public static <@NonNull T> Flowable<T> merge(
             @NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2
      ) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -1560,7 +1560,7 @@ public static <T> Flowable<T> merge(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
+    public static <@NonNull T> Flowable<T> merge(
             @NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2,
             @NonNull MaybeSource<? extends T> source3
      ) {
@@ -1615,7 +1615,7 @@ public static <T> Flowable<T> merge(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
+    public static <@NonNull T> Flowable<T> merge(
             @NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2,
             @NonNull MaybeSource<? extends T> source3, @NonNull MaybeSource<? extends T> source4
      ) {
@@ -1661,7 +1661,7 @@ public static <T> Flowable<T> merge(
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> mergeArray(MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArray(MaybeSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return Flowable.empty();
@@ -1706,7 +1706,7 @@ public static <T> Flowable<T> mergeArray(MaybeSource<? extends T>... sources) {
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> mergeArrayDelayError(@NonNull MaybeSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArrayDelayError(@NonNull MaybeSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         return Flowable.fromArray(sources).flatMapMaybe(Functions.identity(), true, Math.max(1, sources.length));
     }
@@ -1744,7 +1744,7 @@ public static <T> Flowable<T> mergeArrayDelayError(@NonNull MaybeSource<? extend
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).flatMapMaybe(Functions.identity(), true, Integer.MAX_VALUE);
     }
 
@@ -1780,7 +1780,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? exten
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         return mergeDelayError(sources, Integer.MAX_VALUE);
     }
 
@@ -1819,7 +1819,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources, int maxConcurrency) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapMaybePublisher<>(sources, Functions.identity(), true, maxConcurrency));
@@ -1858,7 +1858,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return mergeArrayDelayError(source1, source2);
@@ -1900,7 +1900,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull MaybeSource<? extends T>
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull MaybeSource<? extends T> source1,
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull MaybeSource<? extends T> source1,
             @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -1946,7 +1946,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull MaybeSource<? extends T>
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(
+    public static <@NonNull T> Flowable<T> mergeDelayError(
             @NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2,
             @NonNull MaybeSource<? extends T> source3, @NonNull MaybeSource<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -1976,7 +1976,7 @@ public static <T> Flowable<T> mergeDelayError(
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Maybe<T> never() {
+    public static <@NonNull T> Maybe<T> never() {
         return RxJavaPlugins.onAssembly((Maybe<T>)MaybeNever.INSTANCE);
     }
 
@@ -2003,7 +2003,7 @@ public static <T> Maybe<T> never() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2) {
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate());
     }
 
@@ -2033,7 +2033,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull MaybeSource<? extends T
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<Boolean> sequenceEqual(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2,
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2,
             @NonNull BiPredicate<? super T, ? super T> isEqual) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -2070,7 +2070,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull MaybeSource<? extends T
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapMaybePublisher<>(sources, Functions.identity(), false));
     }
@@ -2105,7 +2105,7 @@ public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends MaybeSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapMaybePublisher<>(sources, Functions.identity(), true));
     }
@@ -2181,7 +2181,7 @@ public static Maybe<Long> timer(long delay, @NonNull TimeUnit unit, @NonNull Sch
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> unsafeCreate(@NonNull MaybeSource<T> onSubscribe) {
+    public static <@NonNull T> Maybe<T> unsafeCreate(@NonNull MaybeSource<T> onSubscribe) {
         if (onSubscribe instanceof Maybe) {
             throw new IllegalArgumentException("unsafeCreate(Maybe) should be upgraded");
         }
@@ -2214,7 +2214,7 @@ public static <T> Maybe<T> unsafeCreate(@NonNull MaybeSource<T> onSubscribe) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, D> Maybe<T> using(@NonNull Supplier<? extends D> resourceSupplier,
+    public static <@NonNull T, @NonNull D> Maybe<T> using(@NonNull Supplier<? extends D> resourceSupplier,
             @NonNull Function<? super D, ? extends MaybeSource<? extends T>> sourceSupplier,
             @NonNull Consumer<? super D> resourceCleanup) {
         return using(resourceSupplier, sourceSupplier, resourceCleanup, true);
@@ -2253,7 +2253,7 @@ public static <T, D> Maybe<T> using(@NonNull Supplier<? extends D> resourceSuppl
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, D> Maybe<T> using(@NonNull Supplier<? extends D> resourceSupplier,
+    public static <@NonNull T, @NonNull D> Maybe<T> using(@NonNull Supplier<? extends D> resourceSupplier,
             @NonNull Function<? super D, ? extends MaybeSource<? extends T>> sourceSupplier,
             @NonNull Consumer<? super D> resourceCleanup, boolean eager) {
         Objects.requireNonNull(resourceSupplier, "resourceSupplier is null");
@@ -2279,7 +2279,7 @@ public static <T, D> Maybe<T> using(@NonNull Supplier<? extends D> resourceSuppl
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Maybe<T> wrap(@NonNull MaybeSource<T> source) {
+    public static <@NonNull T> Maybe<T> wrap(@NonNull MaybeSource<T> source) {
         if (source instanceof Maybe) {
             return RxJavaPlugins.onAssembly((Maybe<T>)source);
         }
@@ -2318,7 +2318,7 @@ public static <T> Maybe<T> wrap(@NonNull MaybeSource<T> source) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Maybe<R> zip(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources, @NonNull Function<? super Object[], ? extends R> zipper) {
+    public static <@NonNull T, @NonNull R> Maybe<R> zip(@NonNull Iterable<@NonNull ? extends MaybeSource<? extends T>> sources, @NonNull Function<? super Object[], ? extends R> zipper) {
         Objects.requireNonNull(zipper, "zipper is null");
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new MaybeZipIterable<>(sources, zipper));
@@ -2354,7 +2354,7 @@ public static <T, R> Maybe<R> zip(@NonNull Iterable<@NonNull ? extends MaybeSour
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -2396,7 +2396,7 @@ public static <T1, T2, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull Function3<? super T1, ? super T2, ? super T3, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -2443,7 +2443,7 @@ public static <T1, T2, T3, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull MaybeSource<? extends T4> source4,
             @NonNull Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> zipper) {
@@ -2495,7 +2495,7 @@ public static <T1, T2, T3, T4, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5,
             @NonNull Function5<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? extends R> zipper) {
@@ -2551,7 +2551,7 @@ public static <T1, T2, T3, T4, T5, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6,
             @NonNull Function6<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? extends R> zipper) {
@@ -2612,7 +2612,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6,
             @NonNull MaybeSource<? extends T7> source7,
@@ -2678,7 +2678,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6,
             @NonNull MaybeSource<? extends T7> source7, @NonNull MaybeSource<? extends T8> source8,
@@ -2747,7 +2747,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Maybe<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Maybe<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull T9, @NonNull R> Maybe<R> zip(
             @NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3,
             @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6,
             @NonNull MaybeSource<? extends T7> source7, @NonNull MaybeSource<? extends T8> source8, @NonNull MaybeSource<? extends T9> source9,
@@ -2798,7 +2798,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Maybe<R> zip(
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T, R> Maybe<R> zipArray(@NonNull Function<? super Object[], ? extends R> zipper,
+    public static <@NonNull T, @NonNull R> Maybe<R> zipArray(@NonNull Function<? super Object[], ? extends R> zipper,
             @NonNull MaybeSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
@@ -3058,7 +3058,7 @@ public final Maybe<T> cache() {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<U> cast(@NonNull Class<? extends U> clazz) {
+    public final <@NonNull U> Maybe<U> cast(@NonNull Class<? extends U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return map(Functions.castFunction(clazz));
     }
@@ -3088,7 +3088,7 @@ public final <U> Maybe<U> cast(@NonNull Class<? extends U> clazz) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Maybe<R> compose(@NonNull MaybeTransformer<? super T, ? extends R> transformer) {
+    public final <@NonNull R> Maybe<R> compose(@NonNull MaybeTransformer<? super T, ? extends R> transformer) {
         return wrap(((MaybeTransformer<T, R>) Objects.requireNonNull(transformer, "transformer is null")).apply(this));
     }
 
@@ -3113,7 +3113,7 @@ public final <R> Maybe<R> compose(@NonNull MaybeTransformer<? super T, ? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> concatMap(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Maybe<R> concatMap(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return flatMap(mapper);
     }
 
@@ -3169,7 +3169,7 @@ public final Completable concatMapCompletable(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Maybe<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return flatMapSingle(mapper);
     }
 
@@ -3444,7 +3444,7 @@ public final Maybe<T> delay(long time, @NonNull TimeUnit unit, @NonNull Schedule
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
-    public final <U> Maybe<T> delay(@NonNull Publisher<U> delayIndicator) {
+    public final <@NonNull U> Maybe<T> delay(@NonNull Publisher<U> delayIndicator) {
         Objects.requireNonNull(delayIndicator, "delayIndicator is null");
         return RxJavaPlugins.onAssembly(new MaybeDelayOtherPublisher<>(this, delayIndicator));
     }
@@ -3471,7 +3471,7 @@ public final <U> Maybe<T> delay(@NonNull Publisher<U> delayIndicator) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> delaySubscription(@NonNull Publisher<U> subscriptionIndicator) {
+    public final <@NonNull U> Maybe<T> delaySubscription(@NonNull Publisher<U> subscriptionIndicator) {
         Objects.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
         return RxJavaPlugins.onAssembly(new MaybeDelaySubscriptionOtherPublisher<>(this, subscriptionIndicator));
     }
@@ -3875,7 +3875,7 @@ public final Maybe<T> filter(@NonNull Predicate<? super T> predicate) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> flatMap(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Maybe<R> flatMap(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatten<>(this, mapper));
     }
@@ -3905,7 +3905,7 @@ public final <R> Maybe<R> flatMap(@NonNull Function<? super T, ? extends MaybeSo
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> flatMap(
+    public final <@NonNull R> Maybe<R> flatMap(
             @NonNull Function<? super T, ? extends MaybeSource<? extends R>> onSuccessMapper,
             @NonNull Function<? super Throwable, ? extends MaybeSource<? extends R>> onErrorMapper,
             @NonNull Supplier<? extends MaybeSource<? extends R>> onCompleteSupplier) {
@@ -3941,7 +3941,7 @@ public final <R> Maybe<R> flatMap(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, R> Maybe<R> flatMap(@NonNull Function<? super T, ? extends MaybeSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Maybe<R> flatMap(@NonNull Function<? super T, ? extends MaybeSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -3974,7 +3974,7 @@ public final <U, R> Maybe<R> flatMap(@NonNull Function<? super T, ? extends Mayb
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<U> flattenAsFlowable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Flowable<U> flattenAsFlowable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatMapIterableFlowable<>(this, mapper));
     }
@@ -4001,7 +4001,7 @@ public final <U> Flowable<U> flattenAsFlowable(@NonNull Function<? super T, ? ex
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Observable<U> flattenAsObservable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Observable<U> flattenAsObservable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatMapIterableObservable<>(this, mapper));
     }
@@ -4026,7 +4026,7 @@ public final <U> Observable<U> flattenAsObservable(@NonNull Function<? super T,
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Observable<R> flatMapObservable(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flatMapObservable(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatMapObservable<>(this, mapper));
     }
@@ -4055,7 +4055,7 @@ public final <R> Observable<R> flatMapObservable(@NonNull Function<? super T, ?
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMapPublisher(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flatMapPublisher(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatMapPublisher<>(this, mapper));
     }
@@ -4084,7 +4084,7 @@ public final <R> Flowable<R> flatMapPublisher(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Maybe<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlatMapSingle<>(this, mapper));
     }
@@ -4324,7 +4324,7 @@ public final Single<Boolean> isEmpty() {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> lift(@NonNull MaybeOperator<? extends R, ? super T> lift) {
+    public final <@NonNull R> Maybe<R> lift(@NonNull MaybeOperator<? extends R, ? super T> lift) {
         Objects.requireNonNull(lift, "lift is null");
         return RxJavaPlugins.onAssembly(new MaybeLift<>(this, lift));
     }
@@ -4349,7 +4349,7 @@ public final <R> Maybe<R> lift(@NonNull MaybeOperator<? extends R, ? super T> li
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> map(@NonNull Function<? super T, ? extends R> mapper) {
+    public final <@NonNull R> Maybe<R> map(@NonNull Function<? super T, ? extends R> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeMap<>(this, mapper));
     }
@@ -4451,7 +4451,7 @@ public final Maybe<T> observeOn(@NonNull Scheduler scheduler) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<U> ofType(@NonNull Class<U> clazz) {
+    public final <@NonNull U> Maybe<U> ofType(@NonNull Class<U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return filter(Functions.isInstanceOf(clazz)).cast(clazz);
     }
@@ -4843,7 +4843,7 @@ public final Flowable<T> repeatUntil(@NonNull BooleanSupplier stop) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Flowable<T> repeatWhen(@NonNull Function<? super Flowable<Object>, ? extends Publisher<@NonNull ?>> handler) {
+    public final Flowable<T> repeatWhen(@NonNull Function<? super Flowable<Object>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         return toFlowable().repeatWhen(handler);
     }
 
@@ -5061,7 +5061,7 @@ public final Maybe<T> retryUntil(@NonNull BooleanSupplier stop) {
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     public final Maybe<T> retryWhen(
-            @NonNull Function<? super Flowable<Throwable>, ? extends Publisher<@NonNull ?>> handler) {
+            @NonNull Function<? super Flowable<Throwable>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         return toFlowable().retryWhen(handler).singleElement();
     }
 
@@ -5517,7 +5517,7 @@ public final Single<T> switchIfEmpty(@NonNull SingleSource<? extends T> other) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> takeUntil(@NonNull MaybeSource<U> other) {
+    public final <@NonNull U> Maybe<T> takeUntil(@NonNull MaybeSource<U> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new MaybeTakeUntilMaybe<>(this, other));
     }
@@ -5548,7 +5548,7 @@ public final <U> Maybe<T> takeUntil(@NonNull MaybeSource<U> other) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> takeUntil(@NonNull Publisher<U> other) {
+    public final <@NonNull U> Maybe<T> takeUntil(@NonNull Publisher<U> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new MaybeTakeUntilPublisher<>(this, other));
     }
@@ -5913,7 +5913,7 @@ public final Maybe<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNull Sch
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> timeout(@NonNull MaybeSource<U> timeoutIndicator) {
+    public final <@NonNull U> Maybe<T> timeout(@NonNull MaybeSource<U> timeoutIndicator) {
         Objects.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
         return RxJavaPlugins.onAssembly(new MaybeTimeoutMaybe<>(this, timeoutIndicator, null));
     }
@@ -5938,7 +5938,7 @@ public final <U> Maybe<T> timeout(@NonNull MaybeSource<U> timeoutIndicator) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> timeout(@NonNull MaybeSource<U> timeoutIndicator, @NonNull MaybeSource<? extends T> fallback) {
+    public final <@NonNull U> Maybe<T> timeout(@NonNull MaybeSource<U> timeoutIndicator, @NonNull MaybeSource<? extends T> fallback) {
         Objects.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
         Objects.requireNonNull(fallback, "fallback is null");
         return RxJavaPlugins.onAssembly(new MaybeTimeoutMaybe<>(this, timeoutIndicator, fallback));
@@ -5966,7 +5966,7 @@ public final <U> Maybe<T> timeout(@NonNull MaybeSource<U> timeoutIndicator, @Non
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> timeout(@NonNull Publisher<U> timeoutIndicator) {
+    public final <@NonNull U> Maybe<T> timeout(@NonNull Publisher<U> timeoutIndicator) {
         Objects.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
         return RxJavaPlugins.onAssembly(new MaybeTimeoutPublisher<>(this, timeoutIndicator, null));
     }
@@ -5995,7 +5995,7 @@ public final <U> Maybe<T> timeout(@NonNull Publisher<U> timeoutIndicator) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<T> timeout(@NonNull Publisher<U> timeoutIndicator, @NonNull MaybeSource<? extends T> fallback) {
+    public final <@NonNull U> Maybe<T> timeout(@NonNull Publisher<U> timeoutIndicator, @NonNull MaybeSource<? extends T> fallback) {
         Objects.requireNonNull(timeoutIndicator, "timeoutIndicator is null");
         Objects.requireNonNull(fallback, "fallback is null");
         return RxJavaPlugins.onAssembly(new MaybeTimeoutPublisher<>(this, timeoutIndicator, fallback));
@@ -6052,7 +6052,7 @@ public final Maybe<T> unsubscribeOn(@NonNull Scheduler scheduler) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, R> Maybe<R> zipWith(@NonNull MaybeSource<? extends U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
+    public final <@NonNull U, @NonNull R> Maybe<R> zipWith(@NonNull MaybeSource<? extends U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
         Objects.requireNonNull(other, "other is null");
         return zip(this, other, zipper);
     }
@@ -6134,7 +6134,7 @@ public final TestObserver<T> test(boolean dispose) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Maybe<@NonNull T> fromOptional(@NonNull Optional<T> optional) {
+    public static <@NonNull T> Maybe<@NonNull T> fromOptional(@NonNull Optional<T> optional) {
         Objects.requireNonNull(optional, "optional is null");
         return optional.map(Maybe::just).orElseGet(Maybe::empty);
     }
@@ -6168,7 +6168,7 @@ public final TestObserver<T> test(boolean dispose) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Maybe<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
+    public static <@NonNull T> Maybe<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
         Objects.requireNonNull(stage, "stage is null");
         return RxJavaPlugins.onAssembly(new MaybeFromCompletionStage<>(stage));
     }
@@ -6304,7 +6304,7 @@ public final CompletionStage<T> toCompletionStage(@Nullable T defaultItem) {
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public final <R> Flowable<R> flattenStreamAsFlowable(@NonNull Function<? super T, ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flattenStreamAsFlowable(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlattenStreamAsFlowable<>(this, mapper));
     }
@@ -6344,7 +6344,7 @@ public final <R> Flowable<R> flattenStreamAsFlowable(@NonNull Function<? super T
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flattenStreamAsObservable(@NonNull Function<? super T, ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flattenStreamAsObservable(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new MaybeFlattenStreamAsObservable<>(this, mapper));
     }
diff --git a/src/main/java/io/reactivex/rxjava3/core/Observable.java b/src/main/java/io/reactivex/rxjava3/core/Observable.java
index 9869276b12..be33a95e3f 100644
--- a/src/main/java/io/reactivex/rxjava3/core/Observable.java
+++ b/src/main/java/io/reactivex/rxjava3/core/Observable.java
@@ -130,7 +130,7 @@ public abstract class Observable<@NonNull T> implements ObservableSource<T> {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> amb(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> amb(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new ObservableAmb<>(null, sources));
     }
@@ -166,7 +166,7 @@ public static <T> Observable<T> amb(@NonNull Iterable<@NonNull ? extends Observa
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Observable<T> ambArray(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> ambArray(@NonNull ObservableSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         int len = sources.length;
         if (len == 0) {
@@ -228,7 +228,7 @@ public static int bufferSize() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, R> Observable<R> combineLatest(
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatest(
             @NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatest(sources, combiner, bufferSize());
@@ -275,7 +275,7 @@ public static <T, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Observable<R> combineLatest(
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatest(
             @NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
@@ -325,7 +325,7 @@ public static <T, R> Observable<R> combineLatest(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, R> Observable<R> combineLatestArray(
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatestArray(
             @NonNull ObservableSource<? extends T>[] sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatestArray(sources, combiner, bufferSize());
@@ -372,7 +372,7 @@ public static <T, R> Observable<R> combineLatestArray(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Observable<R> combineLatestArray(
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatestArray(
             @NonNull ObservableSource<? extends T>[] sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
@@ -419,7 +419,7 @@ public static <T, R> Observable<R> combineLatestArray(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -463,7 +463,7 @@ public static <T1, T2, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3,
             @NonNull Function3<? super T1, ? super T2, ? super T3, ? extends R> combiner) {
@@ -513,7 +513,7 @@ public static <T1, T2, T3, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> combiner) {
@@ -567,7 +567,7 @@ public static <T1, T2, T3, T4, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull ObservableSource<? extends T5> source5,
@@ -626,7 +626,7 @@ public static <T1, T2, T3, T4, T5, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
@@ -690,7 +690,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
@@ -759,7 +759,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
@@ -832,7 +832,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> combineLatest(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> combineLatest(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull T9, @NonNull R> Observable<R> combineLatest(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
@@ -890,7 +890,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> combineLates
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, R> Observable<R> combineLatestArrayDelayError(
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatestArrayDelayError(
             @NonNull ObservableSource<? extends T>[] sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatestArrayDelayError(sources, combiner, bufferSize());
@@ -938,7 +938,7 @@ public static <T, R> Observable<R> combineLatestArrayDelayError(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Observable<R> combineLatestArrayDelayError(@NonNull ObservableSource<? extends T>[] sources,
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatestArrayDelayError(@NonNull ObservableSource<? extends T>[] sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -990,7 +990,7 @@ public static <T, R> Observable<R> combineLatestArrayDelayError(@NonNull Observa
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, R> Observable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner) {
         return combineLatestDelayError(sources, combiner, bufferSize());
     }
@@ -1037,7 +1037,7 @@ public static <T, R> Observable<R> combineLatestDelayError(@NonNull Iterable<@No
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Observable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Observable<R> combineLatestDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> combiner, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -1066,7 +1066,7 @@ public static <T, R> Observable<R> combineLatestDelayError(@NonNull Iterable<@No
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concat(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concat(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return fromIterable(sources).concatMapDelayError((Function)Functions.identity(), false, bufferSize());
     }
@@ -1091,7 +1091,7 @@ public static <T> Observable<T> concat(@NonNull Iterable<@NonNull ? extends Obse
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concat(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concat(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concat(sources, bufferSize());
     }
 
@@ -1119,7 +1119,7 @@ public static <T> Observable<T> concat(@NonNull ObservableSource<? extends Obser
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concat(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
+    public static <@NonNull T> Observable<T> concat(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableConcatMap(sources, Functions.identity(), bufferSize, ErrorMode.IMMEDIATE));
@@ -1147,7 +1147,7 @@ public static <T> Observable<T> concat(@NonNull ObservableSource<? extends Obser
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concat(@NonNull ObservableSource<? extends T> source1, ObservableSource<? extends T> source2) {
+    public static <@NonNull T> Observable<T> concat(@NonNull ObservableSource<? extends T> source1, ObservableSource<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return concatArray(source1, source2);
@@ -1177,7 +1177,7 @@ public static <T> Observable<T> concat(@NonNull ObservableSource<? extends T> so
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concat(
+    public static <@NonNull T> Observable<T> concat(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull ObservableSource<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -1212,7 +1212,7 @@ public static <T> Observable<T> concat(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concat(
+    public static <@NonNull T> Observable<T> concat(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull ObservableSource<? extends T> source3, @NonNull ObservableSource<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -1242,7 +1242,7 @@ public static <T> Observable<T> concat(
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> concatArray(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> concatArray(@NonNull ObservableSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -1271,7 +1271,7 @@ public static <T> Observable<T> concatArray(@NonNull ObservableSource<? extends
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> concatArrayDelayError(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> concatArrayDelayError(@NonNull ObservableSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return empty();
@@ -1306,7 +1306,7 @@ public static <T> Observable<T> concatArrayDelayError(@NonNull ObservableSource<
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Observable<T> concatArrayEager(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> concatArrayEager(@NonNull ObservableSource<? extends T>... sources) {
         return concatArrayEager(bufferSize(), bufferSize(), sources);
     }
 
@@ -1337,7 +1337,7 @@ public static <T> Observable<T> concatArrayEager(@NonNull ObservableSource<? ext
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> concatArrayEager(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> concatArrayEager(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
         return fromArray(sources).concatMapEagerDelayError((Function)Functions.identity(), false, maxConcurrency, bufferSize);
     }
 
@@ -1364,7 +1364,7 @@ public static <T> Observable<T> concatArrayEager(int maxConcurrency, int bufferS
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Observable<T> concatArrayEagerDelayError(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> concatArrayEagerDelayError(@NonNull ObservableSource<? extends T>... sources) {
         return concatArrayEagerDelayError(bufferSize(), bufferSize(), sources);
     }
 
@@ -1396,7 +1396,7 @@ public static <T> Observable<T> concatArrayEagerDelayError(@NonNull ObservableSo
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> concatArrayEagerDelayError(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> concatArrayEagerDelayError(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
         return fromArray(sources).concatMapEagerDelayError((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -1419,7 +1419,7 @@ public static <T> Observable<T> concatArrayEagerDelayError(int maxConcurrency, i
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return concatDelayError(fromIterable(sources));
     }
@@ -1443,7 +1443,7 @@ public static <T> Observable<T> concatDelayError(@NonNull Iterable<@NonNull ? ex
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concatDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concatDelayError(sources, bufferSize(), true);
     }
 
@@ -1470,7 +1470,7 @@ public static <T> Observable<T> concatDelayError(@NonNull ObservableSource<? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concatDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize, boolean tillTheEnd) {
+    public static <@NonNull T> Observable<T> concatDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize, boolean tillTheEnd) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize is null");
         return RxJavaPlugins.onAssembly(new ObservableConcatMap(sources, Functions.identity(), bufferSize, tillTheEnd ? ErrorMode.END : ErrorMode.BOUNDARY));
@@ -1497,7 +1497,7 @@ public static <T> Observable<T> concatDelayError(@NonNull ObservableSource<? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEager(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concatEager(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         return concatEager(sources, bufferSize(), bufferSize());
     }
 
@@ -1528,7 +1528,7 @@ public static <T> Observable<T> concatEager(@NonNull Iterable<@NonNull ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEager(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Observable<T> concatEager(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).concatMapEagerDelayError((Function)Functions.identity(), false, maxConcurrency, bufferSize);
     }
 
@@ -1553,7 +1553,7 @@ public static <T> Observable<T> concatEager(@NonNull Iterable<@NonNull ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEager(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concatEager(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concatEager(sources, bufferSize(), bufferSize());
     }
 
@@ -1585,7 +1585,7 @@ public static <T> Observable<T> concatEager(@NonNull ObservableSource<? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEager(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Observable<T> concatEager(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return wrap(sources).concatMapEager((Function)Functions.identity(), maxConcurrency, bufferSize);
     }
 
@@ -1611,7 +1611,7 @@ public static <T> Observable<T> concatEager(@NonNull ObservableSource<? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         return concatEagerDelayError(sources, bufferSize(), bufferSize());
     }
 
@@ -1643,7 +1643,7 @@ public static <T> Observable<T> concatEagerDelayError(@NonNull Iterable<@NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Observable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).concatMapEagerDelayError((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -1669,7 +1669,7 @@ public static <T> Observable<T> concatEagerDelayError(@NonNull Iterable<@NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEagerDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concatEagerDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return concatEagerDelayError(sources, bufferSize(), bufferSize());
     }
 
@@ -1700,7 +1700,7 @@ public static <T> Observable<T> concatEagerDelayError(@NonNull ObservableSource<
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> concatEagerDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Observable<T> concatEagerDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return wrap(sources).concatMapEagerDelayError((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -1758,7 +1758,7 @@ public static <T> Observable<T> concatEagerDelayError(@NonNull ObservableSource<
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> create(@NonNull ObservableOnSubscribe<T> source) {
+    public static <@NonNull T> Observable<T> create(@NonNull ObservableOnSubscribe<T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new ObservableCreate<>(source));
     }
@@ -1790,7 +1790,7 @@ public static <T> Observable<T> create(@NonNull ObservableOnSubscribe<T> source)
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> defer(@NonNull Supplier<? extends ObservableSource<? extends T>> supplier) {
+    public static <@NonNull T> Observable<T> defer(@NonNull Supplier<? extends ObservableSource<? extends T>> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new ObservableDefer<>(supplier));
     }
@@ -1814,7 +1814,7 @@ public static <T> Observable<T> defer(@NonNull Supplier<? extends ObservableSour
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Observable<T> empty() {
+    public static <@NonNull T> Observable<T> empty() {
         return RxJavaPlugins.onAssembly((Observable<T>) ObservableEmpty.INSTANCE);
     }
 
@@ -1839,7 +1839,7 @@ public static <T> Observable<T> empty() {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> error(@NonNull Supplier<? extends Throwable> supplier) {
+    public static <@NonNull T> Observable<T> error(@NonNull Supplier<? extends Throwable> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new ObservableError<>(supplier));
     }
@@ -1865,7 +1865,7 @@ public static <T> Observable<T> error(@NonNull Supplier<? extends Throwable> sup
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> error(@NonNull Throwable throwable) {
+    public static <@NonNull T> Observable<T> error(@NonNull Throwable throwable) {
         Objects.requireNonNull(throwable, "throwable is null");
         return error(Functions.justSupplier(throwable));
     }
@@ -1895,7 +1895,7 @@ public static <T> Observable<T> error(@NonNull Throwable throwable) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromAction(@NonNull Action action) {
+    public static <@NonNull T> Observable<T> fromAction(@NonNull Action action) {
         Objects.requireNonNull(action, "action is null");
         return RxJavaPlugins.onAssembly(new ObservableFromAction<>(action));
     }
@@ -1921,7 +1921,7 @@ public static <T> Observable<T> fromAction(@NonNull Action action) {
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> fromArray(@NonNull T... items) {
+    public static <@NonNull T> Observable<T> fromArray(@NonNull T... items) {
         Objects.requireNonNull(items, "items is null");
         if (items.length == 0) {
             return empty();
@@ -1965,7 +1965,7 @@ public static <T> Observable<T> fromArray(@NonNull T... items) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromCallable(@NonNull Callable<? extends T> callable) {
+    public static <@NonNull T> Observable<T> fromCallable(@NonNull Callable<? extends T> callable) {
         Objects.requireNonNull(callable, "callable is null");
         return RxJavaPlugins.onAssembly(new ObservableFromCallable<>(callable));
     }
@@ -1986,7 +1986,7 @@ public static <T> Observable<T> fromCallable(@NonNull Callable<? extends T> call
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromCompletable(@NonNull CompletableSource completableSource) {
+    public static <@NonNull T> Observable<T> fromCompletable(@NonNull CompletableSource completableSource) {
         Objects.requireNonNull(completableSource, "completableSource is null");
         return RxJavaPlugins.onAssembly(new ObservableFromCompletable<>(completableSource));
     }
@@ -2024,7 +2024,7 @@ public static <T> Observable<T> fromCompletable(@NonNull CompletableSource compl
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromFuture(@NonNull Future<? extends T> future) {
+    public static <@NonNull T> Observable<T> fromFuture(@NonNull Future<? extends T> future) {
         Objects.requireNonNull(future, "future is null");
         return RxJavaPlugins.onAssembly(new ObservableFromFuture<>(future, 0L, null));
     }
@@ -2066,7 +2066,7 @@ public static <T> Observable<T> fromFuture(@NonNull Future<? extends T> future)
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromFuture(@NonNull Future<? extends T> future, long timeout, @NonNull TimeUnit unit) {
+    public static <@NonNull T> Observable<T> fromFuture(@NonNull Future<? extends T> future, long timeout, @NonNull TimeUnit unit) {
         Objects.requireNonNull(future, "future is null");
         Objects.requireNonNull(unit, "unit is null");
         return RxJavaPlugins.onAssembly(new ObservableFromFuture<>(future, timeout, unit));
@@ -2094,7 +2094,7 @@ public static <T> Observable<T> fromFuture(@NonNull Future<? extends T> future,
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromIterable(@NonNull Iterable<@NonNull ? extends T> source) {
+    public static <@NonNull T> Observable<T> fromIterable(@NonNull Iterable<? extends T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new ObservableFromIterable<>(source));
     }
@@ -2118,7 +2118,7 @@ public static <T> Observable<T> fromIterable(@NonNull Iterable<@NonNull ? extend
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
+    public static <@NonNull T> Observable<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
         Objects.requireNonNull(maybe, "maybe is null");
         return RxJavaPlugins.onAssembly(new MaybeToObservable<>(maybe));
     }
@@ -2155,7 +2155,7 @@ public static <T> Observable<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromPublisher(@NonNull Publisher<@NonNull ? extends T> publisher) {
+    public static <@NonNull T> Observable<T> fromPublisher(@NonNull Publisher<? extends T> publisher) {
         Objects.requireNonNull(publisher, "publisher is null");
         return RxJavaPlugins.onAssembly(new ObservableFromPublisher<>(publisher));
     }
@@ -2191,7 +2191,7 @@ public static <T> Observable<T> fromPublisher(@NonNull Publisher<@NonNull ? exte
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromRunnable(@NonNull Runnable run) {
+    public static <@NonNull T> Observable<T> fromRunnable(@NonNull Runnable run) {
         Objects.requireNonNull(run, "run is null");
         return RxJavaPlugins.onAssembly(new ObservableFromRunnable<>(run));
     }
@@ -2214,7 +2214,7 @@ public static <T> Observable<T> fromRunnable(@NonNull Runnable run) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromSingle(@NonNull SingleSource<T> source) {
+    public static <@NonNull T> Observable<T> fromSingle(@NonNull SingleSource<T> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new SingleToObservable<>(source));
     }
@@ -2252,7 +2252,7 @@ public static <T> Observable<T> fromSingle(@NonNull SingleSource<T> source) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> fromSupplier(@NonNull Supplier<? extends T> supplier) {
+    public static <@NonNull T> Observable<T> fromSupplier(@NonNull Supplier<? extends T> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new ObservableFromSupplier<>(supplier));
     }
@@ -2282,7 +2282,7 @@ public static <T> Observable<T> fromSupplier(@NonNull Supplier<? extends T> supp
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> generate(@NonNull Consumer<Emitter<T>> generator) {
+    public static <@NonNull T> Observable<T> generate(@NonNull Consumer<Emitter<T>> generator) {
         Objects.requireNonNull(generator, "generator is null");
         return generate(Functions.nullSupplier(),
                 ObservableInternalHelper.simpleGenerator(generator), Functions.emptyConsumer());
@@ -2315,7 +2315,7 @@ public static <T> Observable<T> generate(@NonNull Consumer<Emitter<T>> generator
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, S> Observable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiConsumer<S, Emitter<T>> generator) {
+    public static <@NonNull T, @NonNull S> Observable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiConsumer<S, Emitter<T>> generator) {
         Objects.requireNonNull(generator, "generator is null");
         return generate(initialState, ObservableInternalHelper.simpleBiGenerator(generator), Functions.emptyConsumer());
     }
@@ -2349,7 +2349,7 @@ public static <T, S> Observable<T> generate(@NonNull Supplier<S> initialState, @
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, S> Observable<T> generate(
+    public static <@NonNull T, @NonNull S> Observable<T> generate(
             @NonNull Supplier<S> initialState,
             @NonNull BiConsumer<S, Emitter<T>> generator,
             @NonNull Consumer<? super S> disposeState) {
@@ -2385,7 +2385,7 @@ public static <T, S> Observable<T> generate(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, S> Observable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, Emitter<T>, S> generator) {
+    public static <@NonNull T, @NonNull S> Observable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, Emitter<T>, S> generator) {
         return generate(initialState, generator, Functions.emptyConsumer());
     }
 
@@ -2419,7 +2419,7 @@ public static <T, S> Observable<T> generate(@NonNull Supplier<S> initialState, @
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, S> Observable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, Emitter<T>, S> generator,
+    public static <@NonNull T, @NonNull S> Observable<T> generate(@NonNull Supplier<S> initialState, @NonNull BiFunction<S, Emitter<T>, S> generator,
             @NonNull Consumer<? super S> disposeState) {
         Objects.requireNonNull(initialState, "initialState is null");
         Objects.requireNonNull(generator, "generator is null");
@@ -2643,7 +2643,7 @@ public static Observable<Long> intervalRange(long start, long count, long initia
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item) {
         Objects.requireNonNull(item, "item is null");
         return RxJavaPlugins.onAssembly(new ObservableJust<>(item));
     }
@@ -2670,7 +2670,7 @@ public static <T> Observable<T> just(@NonNull T item) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
 
@@ -2701,7 +2701,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -2735,7 +2735,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -2773,7 +2773,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -2814,7 +2814,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -2859,7 +2859,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -2907,7 +2907,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7, @NonNull T item8) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7, @NonNull T item8) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -2958,7 +2958,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7, @NonNull T item8, @NonNull T item9) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7, @NonNull T item8, @NonNull T item9) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -3013,7 +3013,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7, @NonNull T item8, @NonNull T item9, @NonNull T item10) {
+    public static <@NonNull T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNull T item3, @NonNull T item4, @NonNull T item5, @NonNull T item6, @NonNull T item7, @NonNull T item8, @NonNull T item9, @NonNull T item10) {
         Objects.requireNonNull(item1, "item1 is null");
         Objects.requireNonNull(item2, "item2 is null");
         Objects.requireNonNull(item3, "item3 is null");
@@ -3072,7 +3072,7 @@ public static <T> Observable<T> just(@NonNull T item1, @NonNull T item2, @NonNul
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), false, maxConcurrency, bufferSize);
     }
 
@@ -3121,7 +3121,7 @@ public static <T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends Obser
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> mergeArray(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> mergeArray(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), false, maxConcurrency, bufferSize);
     }
 
@@ -3162,7 +3162,7 @@ public static <T> Observable<T> mergeArray(int maxConcurrency, int bufferSize, @
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         return fromIterable(sources).flatMap((Function)Functions.identity());
     }
 
@@ -3208,7 +3208,7 @@ public static <T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends Obser
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), maxConcurrency);
     }
 
@@ -3250,7 +3250,7 @@ public static <T> Observable<T> merge(@NonNull Iterable<@NonNull ? extends Obser
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @NonNull
-    public static <T> Observable<T> merge(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> merge(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new ObservableFlatMap(sources, Functions.identity(), false, Integer.MAX_VALUE, bufferSize()));
     }
@@ -3299,7 +3299,7 @@ public static <T> Observable<T> merge(@NonNull ObservableSource<? extends Observ
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Observable<T> merge(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         return RxJavaPlugins.onAssembly(new ObservableFlatMap(sources, Functions.identity(), false, maxConcurrency, bufferSize()));
@@ -3344,7 +3344,7 @@ public static <T> Observable<T> merge(@NonNull ObservableSource<? extends Observ
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(@NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2) {
+    public static <@NonNull T> Observable<T> merge(@NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return fromArray(source1, source2).flatMap((Function)Functions.identity(), false, 2);
@@ -3391,7 +3391,7 @@ public static <T> Observable<T> merge(@NonNull ObservableSource<? extends T> sou
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(
+    public static <@NonNull T> Observable<T> merge(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull ObservableSource<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -3443,7 +3443,7 @@ public static <T> Observable<T> merge(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> merge(
+    public static <@NonNull T> Observable<T> merge(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull ObservableSource<? extends T> source3, @NonNull ObservableSource<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -3491,7 +3491,7 @@ public static <T> Observable<T> merge(
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> mergeArray(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> mergeArray(@NonNull ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), sources.length);
     }
 
@@ -3524,7 +3524,7 @@ public static <T> Observable<T> mergeArray(@NonNull ObservableSource<? extends T
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true);
     }
 
@@ -3562,7 +3562,7 @@ public static <T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
+    public static <@NonNull T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency, int bufferSize) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -3601,7 +3601,7 @@ public static <T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? ext
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> mergeArrayDelayError(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> mergeArrayDelayError(int maxConcurrency, int bufferSize, @NonNull ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), true, maxConcurrency, bufferSize);
     }
 
@@ -3637,7 +3637,7 @@ public static <T> Observable<T> mergeArrayDelayError(int maxConcurrency, int buf
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         return fromIterable(sources).flatMap((Function)Functions.identity(), true, maxConcurrency);
     }
 
@@ -3670,7 +3670,7 @@ public static <T> Observable<T> mergeDelayError(@NonNull Iterable<@NonNull ? ext
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @NonNull
-    public static <T> Observable<T> mergeDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> mergeDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new ObservableFlatMap(sources, Functions.identity(), true, Integer.MAX_VALUE, bufferSize()));
     }
@@ -3709,7 +3709,7 @@ public static <T> Observable<T> mergeDelayError(@NonNull ObservableSource<? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Observable<T> mergeDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
         return RxJavaPlugins.onAssembly(new ObservableFlatMap(sources, Functions.identity(), true, maxConcurrency, bufferSize()));
@@ -3746,7 +3746,7 @@ public static <T> Observable<T> mergeDelayError(@NonNull ObservableSource<? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(
+    public static <@NonNull T> Observable<T> mergeDelayError(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2) {
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
@@ -3787,7 +3787,7 @@ public static <T> Observable<T> mergeDelayError(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(
+    public static <@NonNull T> Observable<T> mergeDelayError(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull ObservableSource<? extends T> source3) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -3832,7 +3832,7 @@ public static <T> Observable<T> mergeDelayError(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> mergeDelayError(
+    public static <@NonNull T> Observable<T> mergeDelayError(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull ObservableSource<? extends T> source3, @NonNull ObservableSource<? extends T> source4) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -3872,7 +3872,7 @@ public static <T> Observable<T> mergeDelayError(
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
     @SafeVarargs
-    public static <T> Observable<T> mergeArrayDelayError(@NonNull ObservableSource<? extends T>... sources) {
+    public static <@NonNull T> Observable<T> mergeArrayDelayError(@NonNull ObservableSource<? extends T>... sources) {
         return fromArray(sources).flatMap((Function)Functions.identity(), true, sources.length);
     }
 
@@ -3896,7 +3896,7 @@ public static <T> Observable<T> mergeArrayDelayError(@NonNull ObservableSource<?
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Observable<T> never() {
+    public static <@NonNull T> Observable<T> never() {
         return RxJavaPlugins.onAssembly((Observable<T>) ObservableNever.INSTANCE);
     }
 
@@ -4007,7 +4007,7 @@ public static Observable<Long> rangeLong(long start, long count) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(@NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2) {
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate(), bufferSize());
     }
 
@@ -4037,7 +4037,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull ObservableSource<? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(
+    public static <@NonNull T> Single<Boolean> sequenceEqual(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull BiPredicate<? super T, ? super T> isEqual) {
         return sequenceEqual(source1, source2, isEqual, bufferSize());
@@ -4072,7 +4072,7 @@ public static <T> Single<Boolean> sequenceEqual(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(
+    public static <@NonNull T> Single<Boolean> sequenceEqual(
             @NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             @NonNull BiPredicate<? super T, ? super T> isEqual, int bufferSize) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -4108,7 +4108,7 @@ public static <T> Single<Boolean> sequenceEqual(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<Boolean> sequenceEqual(@NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull ObservableSource<? extends T> source1, @NonNull ObservableSource<? extends T> source2,
             int bufferSize) {
         return sequenceEqual(source1, source2, ObjectHelper.equalsPredicate(), bufferSize);
     }
@@ -4145,7 +4145,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull ObservableSource<? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> switchOnNext(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
+    public static <@NonNull T> Observable<T> switchOnNext(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableSwitchMap(sources, Functions.identity(), bufferSize, false));
@@ -4179,7 +4179,7 @@ public static <T> Observable<T> switchOnNext(@NonNull ObservableSource<? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> switchOnNext(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> switchOnNext(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return switchOnNext(sources, bufferSize());
     }
 
@@ -4213,7 +4213,7 @@ public static <T> Observable<T> switchOnNext(@NonNull ObservableSource<? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> switchOnNextDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> switchOnNextDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources) {
         return switchOnNextDelayError(sources, bufferSize());
     }
 
@@ -4251,7 +4251,7 @@ public static <T> Observable<T> switchOnNextDelayError(@NonNull ObservableSource
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> switchOnNextDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
+    public static <@NonNull T> Observable<T> switchOnNextDelayError(@NonNull ObservableSource<? extends ObservableSource<? extends T>> sources, int bufferSize) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableSwitchMap(sources, Functions.identity(), bufferSize, true));
@@ -4331,7 +4331,7 @@ public static Observable<Long> timer(long delay, @NonNull TimeUnit unit, @NonNul
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> unsafeCreate(@NonNull ObservableSource<T> onSubscribe) {
+    public static <@NonNull T> Observable<T> unsafeCreate(@NonNull ObservableSource<T> onSubscribe) {
         Objects.requireNonNull(onSubscribe, "onSubscribe is null");
         if (onSubscribe instanceof Observable) {
             throw new IllegalArgumentException("unsafeCreate(Observable) should be upgraded");
@@ -4365,7 +4365,7 @@ public static <T> Observable<T> unsafeCreate(@NonNull ObservableSource<T> onSubs
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, D> Observable<T> using(
+    public static <@NonNull T, @NonNull D> Observable<T> using(
             @NonNull Supplier<? extends D> resourceSupplier,
             @NonNull Function<? super D, ? extends ObservableSource<? extends T>> sourceSupplier,
             @NonNull Consumer<? super D> resourceCleanup) {
@@ -4404,7 +4404,7 @@ public static <T, D> Observable<T> using(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, D> Observable<T> using(
+    public static <@NonNull T, @NonNull D> Observable<T> using(
             @NonNull Supplier<? extends D> resourceSupplier,
             @NonNull Function<? super D, ? extends ObservableSource<? extends T>> sourceSupplier,
             @NonNull Consumer<? super D> resourceCleanup, boolean eager) {
@@ -4430,7 +4430,7 @@ public static <T, D> Observable<T> using(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<T> wrap(@NonNull ObservableSource<T> source) {
+    public static <@NonNull T> Observable<T> wrap(@NonNull ObservableSource<T> source) {
         Objects.requireNonNull(source, "source is null");
         if (source instanceof Observable) {
             return RxJavaPlugins.onAssembly((Observable<T>)source);
@@ -4487,7 +4487,7 @@ public static <T> Observable<T> wrap(@NonNull ObservableSource<T> source) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, R> Observable<R> zip(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, @NonNull Function<? super Object[], ? extends R> zipper) {
+    public static <@NonNull T, @NonNull R> Observable<R> zip(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources, @NonNull Function<? super Object[], ? extends R> zipper) {
         Objects.requireNonNull(zipper, "zipper is null");
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new ObservableZip<>(null, sources, zipper, bufferSize(), false));
@@ -4548,7 +4548,7 @@ public static <T, R> Observable<R> zip(@NonNull Iterable<@NonNull ? extends Obse
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, R> Observable<R> zip(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Observable<R> zip(@NonNull Iterable<@NonNull ? extends ObservableSource<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> zipper, boolean delayError,
             int bufferSize) {
         Objects.requireNonNull(zipper, "zipper is null");
@@ -4605,7 +4605,7 @@ public static <T, R> Observable<R> zip(@NonNull Iterable<@NonNull ? extends Obse
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -4663,7 +4663,7 @@ public static <T1, T2, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper, boolean delayError) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -4723,7 +4723,7 @@ public static <T1, T2, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper, boolean delayError, int bufferSize) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -4784,7 +4784,7 @@ public static <T1, T2, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3,
             @NonNull Function3<? super T1, ? super T2, ? super T3, ? extends R> zipper) {
@@ -4851,7 +4851,7 @@ public static <T1, T2, T3, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, T4, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2,
             @NonNull ObservableSource<? extends T3> source3, @NonNull ObservableSource<? extends T4> source4,
             @NonNull Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> zipper) {
@@ -4922,7 +4922,7 @@ public static <T1, T2, T3, T4, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, T4, T5, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2, @NonNull ObservableSource<? extends T3> source3,
             @NonNull ObservableSource<? extends T4> source4, @NonNull ObservableSource<? extends T5> source5,
             @NonNull Function5<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? extends R> zipper) {
@@ -4996,7 +4996,7 @@ public static <T1, T2, T3, T4, T5, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, T4, T5, T6, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2, @NonNull ObservableSource<? extends T3> source3,
             @NonNull ObservableSource<? extends T4> source4, @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
             @NonNull Function6<? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? extends R> zipper) {
@@ -5075,7 +5075,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2, @NonNull ObservableSource<? extends T3> source3,
             @NonNull ObservableSource<? extends T4> source4, @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
             @NonNull ObservableSource<? extends T7> source7,
@@ -5159,7 +5159,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2, @NonNull ObservableSource<? extends T3> source3,
             @NonNull ObservableSource<? extends T4> source4, @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
             @NonNull ObservableSource<? extends T7> source7, @NonNull ObservableSource<? extends T8> source8,
@@ -5247,7 +5247,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Observable<R> zip(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull T9, @NonNull R> Observable<R> zip(
             @NonNull ObservableSource<? extends T1> source1, @NonNull ObservableSource<? extends T2> source2, @NonNull ObservableSource<? extends T3> source3,
             @NonNull ObservableSource<? extends T4> source4, @NonNull ObservableSource<? extends T5> source5, @NonNull ObservableSource<? extends T6> source6,
             @NonNull ObservableSource<? extends T7> source7, @NonNull ObservableSource<? extends T8> source8, @NonNull ObservableSource<? extends T9> source9,
@@ -5321,7 +5321,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Observable<R> zip(
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T, R> Observable<R> zipArray(
+    public static <@NonNull T, @NonNull R> Observable<R> zipArray(
             @NonNull Function<? super Object[], ? extends R> zipper,
             boolean delayError, int bufferSize,
             @NonNull ObservableSource<? extends T>... sources) {
@@ -6046,7 +6046,7 @@ public final void blockingSubscribe(@NonNull Observer<? super T> observer) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U extends Collection<? super T>> Observable<U> buffer(int count, int skip, @NonNull Supplier<U> bufferSupplier) {
+    public final <@NonNull U extends Collection<? super T>> Observable<U> buffer(int count, int skip, @NonNull Supplier<U> bufferSupplier) {
         ObjectHelper.verifyPositive(count, "count");
         ObjectHelper.verifyPositive(skip, "skip");
         Objects.requireNonNull(bufferSupplier, "bufferSupplier is null");
@@ -6399,7 +6399,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, i
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <TOpening, TClosing> Observable<@NonNull List<T>> buffer(
+    public final <@NonNull TOpening, @NonNull TClosing> Observable<@NonNull List<T>> buffer(
             @NonNull ObservableSource<? extends TOpening> openingIndicator,
             @NonNull Function<? super TOpening, ? extends ObservableSource<? extends TClosing>> closingIndicator) {
         return buffer(openingIndicator, closingIndicator, ArrayListSupplier.asSupplier());
@@ -6436,7 +6436,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, i
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <TOpening, TClosing, @NonNull U extends Collection<? super T>> Observable<U> buffer(
+    public final <@NonNull TOpening, @NonNull TClosing, @NonNull U extends Collection<? super T>> Observable<U> buffer(
             @NonNull ObservableSource<? extends TOpening> openingIndicator,
             @NonNull Function<? super TOpening, ? extends ObservableSource<? extends TClosing>> closingIndicator,
             @NonNull Supplier<U> bufferSupplier) {
@@ -6473,7 +6473,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, i
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Observable<@NonNull List<T>> buffer(@NonNull ObservableSource<B> boundaryIndicator) {
+    public final <@NonNull B> Observable<@NonNull List<T>> buffer(@NonNull ObservableSource<B> boundaryIndicator) {
         return buffer(boundaryIndicator, ArrayListSupplier.asSupplier());
     }
 
@@ -6507,7 +6507,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, i
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Observable<@NonNull List<T>> buffer(@NonNull ObservableSource<B> boundaryIndicator, int initialCapacity) {
+    public final <@NonNull B> Observable<@NonNull List<T>> buffer(@NonNull ObservableSource<B> boundaryIndicator, int initialCapacity) {
         ObjectHelper.verifyPositive(initialCapacity, "initialCapacity");
         return buffer(boundaryIndicator, Functions.createArrayList(initialCapacity));
     }
@@ -6543,7 +6543,7 @@ public final <U extends Collection<? super T>> Observable<U> buffer(int count, i
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B, @NonNull U extends Collection<? super T>> Observable<U> buffer(@NonNull ObservableSource<B> boundaryIndicator, @NonNull Supplier<U> bufferSupplier) {
+    public final <@NonNull B, @NonNull U extends Collection<? super T>> Observable<U> buffer(@NonNull ObservableSource<B> boundaryIndicator, @NonNull Supplier<U> bufferSupplier) {
         Objects.requireNonNull(boundaryIndicator, "boundaryIndicator is null");
         Objects.requireNonNull(bufferSupplier, "bufferSupplier is null");
         return RxJavaPlugins.onAssembly(new ObservableBufferExactBoundary<>(this, boundaryIndicator, bufferSupplier));
@@ -6688,7 +6688,7 @@ public final Observable<T> cacheWithInitialCapacity(int initialCapacity) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<U> cast(@NonNull Class<U> clazz) {
+    public final <@NonNull U> Observable<U> cast(@NonNull Class<U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return map(Functions.castFunction(clazz));
     }
@@ -6722,7 +6722,7 @@ public final <U> Observable<U> cast(@NonNull Class<U> clazz) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Single<U> collect(@NonNull Supplier<? extends U> initialItemSupplier, @NonNull BiConsumer<? super U, ? super T> collector) {
+    public final <@NonNull U> Single<U> collect(@NonNull Supplier<? extends U> initialItemSupplier, @NonNull BiConsumer<? super U, ? super T> collector) {
         Objects.requireNonNull(initialItemSupplier, "initialItemSupplier is null");
         Objects.requireNonNull(collector, "collector is null");
         return RxJavaPlugins.onAssembly(new ObservableCollectSingle<>(this, initialItemSupplier, collector));
@@ -6757,7 +6757,7 @@ public final <U> Single<U> collect(@NonNull Supplier<? extends U> initialItemSup
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Single<U> collectInto(@NonNull U initialItem, @NonNull BiConsumer<? super U, ? super T> collector) {
+    public final <@NonNull U> Single<U> collectInto(@NonNull U initialItem, @NonNull BiConsumer<? super U, ? super T> collector) {
         Objects.requireNonNull(initialItem, "initialItem is null");
         return collect(Functions.justSupplier(initialItem), collector);
     }
@@ -6786,7 +6786,7 @@ public final <U> Single<U> collectInto(@NonNull U initialItem, @NonNull BiConsum
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> compose(@NonNull ObservableTransformer<? super T, ? extends R> composer) {
+    public final <@NonNull R> Observable<R> compose(@NonNull ObservableTransformer<? super T, ? extends R> composer) {
         return wrap(((ObservableTransformer<T, R>) Objects.requireNonNull(composer, "composer is null")).apply(this));
     }
 
@@ -6817,7 +6817,7 @@ public final <R> Observable<R> compose(@NonNull ObservableTransformer<? super T,
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return concatMap(mapper, 2);
     }
 
@@ -6851,7 +6851,7 @@ public final <R> Observable<R> concatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Observable<R> concatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         if (this instanceof ScalarSupplier) {
@@ -6896,7 +6896,7 @@ public final <R> Observable<R> concatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <R> Observable<R> concatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize, @NonNull Scheduler scheduler) {
+    public final <@NonNull R> Observable<R> concatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -6928,7 +6928,7 @@ public final <R> Observable<R> concatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return concatMapDelayError(mapper, true, bufferSize());
     }
 
@@ -6963,7 +6963,7 @@ public final <R> Observable<R> concatMapDelayError(@NonNull Function<? super T,
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
+    public final <@NonNull R> Observable<R> concatMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean tillTheEnd, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -7008,7 +7008,7 @@ public final <R> Observable<R> concatMapDelayError(@NonNull Function<? super T,
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <R> Observable<R> concatMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
+    public final <@NonNull R> Observable<R> concatMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean tillTheEnd, int bufferSize, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
@@ -7039,7 +7039,7 @@ public final <R> Observable<R> concatMapDelayError(@NonNull Function<? super T,
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapEager(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapEager(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return concatMapEager(mapper, Integer.MAX_VALUE, bufferSize());
     }
 
@@ -7069,7 +7069,7 @@ public final <R> Observable<R> concatMapEager(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapEager(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
+    public final <@NonNull R> Observable<R> concatMapEager(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             int maxConcurrency, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -7103,7 +7103,7 @@ public final <R> Observable<R> concatMapEager(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapEagerDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
+    public final <@NonNull R> Observable<R> concatMapEagerDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean tillTheEnd) {
         return concatMapEagerDelayError(mapper, tillTheEnd, Integer.MAX_VALUE, bufferSize());
     }
@@ -7139,7 +7139,7 @@ public final <R> Observable<R> concatMapEagerDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapEagerDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
+    public final <@NonNull R> Observable<R> concatMapEagerDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean tillTheEnd, int maxConcurrency, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -7318,7 +7318,7 @@ public final Completable concatMapCompletableDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<U> concatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Observable<U> concatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableFlattenIterable<>(this, mapper));
     }
@@ -7347,7 +7347,7 @@ public final <U> Observable<U> concatMapIterable(@NonNull Function<? super T, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return concatMapMaybe(mapper, 2);
     }
 
@@ -7378,7 +7378,7 @@ public final <R> Observable<R> concatMapMaybe(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Observable<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableConcatMapMaybe<>(this, mapper, ErrorMode.IMMEDIATE, bufferSize));
@@ -7408,7 +7408,7 @@ public final <R> Observable<R> concatMapMaybe(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return concatMapMaybeDelayError(mapper, true, 2);
     }
 
@@ -7442,7 +7442,7 @@ public final <R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd) {
+    public final <@NonNull R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd) {
         return concatMapMaybeDelayError(mapper, tillTheEnd, 2);
     }
 
@@ -7478,7 +7478,7 @@ public final <R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd, int bufferSize) {
+    public final <@NonNull R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean tillTheEnd, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableConcatMapMaybe<>(this, mapper, tillTheEnd ? ErrorMode.END : ErrorMode.BOUNDARY, bufferSize));
@@ -7508,7 +7508,7 @@ public final <R> Observable<R> concatMapMaybeDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return concatMapSingle(mapper, 2);
     }
 
@@ -7539,7 +7539,7 @@ public final <R> Observable<R> concatMapSingle(@NonNull Function<? super T, ? ex
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Observable<R> concatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableConcatMapSingle<>(this, mapper, ErrorMode.IMMEDIATE, bufferSize));
@@ -7569,7 +7569,7 @@ public final <R> Observable<R> concatMapSingle(@NonNull Function<? super T, ? ex
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return concatMapSingleDelayError(mapper, true, 2);
     }
 
@@ -7603,7 +7603,7 @@ public final <R> Observable<R> concatMapSingleDelayError(@NonNull Function<? sup
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd) {
+    public final <@NonNull R> Observable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd) {
         return concatMapSingleDelayError(mapper, tillTheEnd, 2);
     }
 
@@ -7639,7 +7639,7 @@ public final <R> Observable<R> concatMapSingleDelayError(@NonNull Function<? sup
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd, int bufferSize) {
+    public final <@NonNull R> Observable<R> concatMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean tillTheEnd, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableConcatMapSingle<>(this, mapper, tillTheEnd ? ErrorMode.END : ErrorMode.BOUNDARY, bufferSize));
@@ -7812,7 +7812,7 @@ public final Single<Long> count() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> debounce(@NonNull Function<? super T, ? extends ObservableSource<U>> debounceIndicator) {
+    public final <@NonNull U> Observable<T> debounce(@NonNull Function<? super T, ? extends ObservableSource<U>> debounceIndicator) {
         Objects.requireNonNull(debounceIndicator, "debounceIndicator is null");
         return RxJavaPlugins.onAssembly(new ObservableDebounce<>(this, debounceIndicator));
     }
@@ -7949,7 +7949,7 @@ public final Observable<T> defaultIfEmpty(@NonNull T defaultItem) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> delay(@NonNull Function<? super T, ? extends ObservableSource<U>> itemDelayIndicator) {
+    public final <@NonNull U> Observable<T> delay(@NonNull Function<? super T, ? extends ObservableSource<U>> itemDelayIndicator) {
         Objects.requireNonNull(itemDelayIndicator, "itemDelayIndicator is null");
         return flatMap(ObservableInternalHelper.itemDelay(itemDelayIndicator));
     }
@@ -8101,7 +8101,7 @@ public final Observable<T> delay(long time, @NonNull TimeUnit unit, @NonNull Sch
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Observable<T> delay(@NonNull ObservableSource<U> subscriptionIndicator,
+    public final <@NonNull U, @NonNull V> Observable<T> delay(@NonNull ObservableSource<U> subscriptionIndicator,
             @NonNull Function<? super T, ? extends ObservableSource<V>> itemDelayIndicator) {
         return delaySubscription(subscriptionIndicator).delay(itemDelayIndicator);
     }
@@ -8126,7 +8126,7 @@ public final <U, V> Observable<T> delay(@NonNull ObservableSource<U> subscriptio
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> delaySubscription(@NonNull ObservableSource<U> subscriptionIndicator) {
+    public final <@NonNull U> Observable<T> delaySubscription(@NonNull ObservableSource<U> subscriptionIndicator) {
         Objects.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
         return RxJavaPlugins.onAssembly(new ObservableDelaySubscriptionOther<>(this, subscriptionIndicator));
     }
@@ -8232,7 +8232,7 @@ public final Observable<T> delaySubscription(long time, @NonNull TimeUnit unit,
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> dematerialize(@NonNull Function<? super T, Notification<R>> selector) {
+    public final <@NonNull R> Observable<R> dematerialize(@NonNull Function<? super T, Notification<R>> selector) {
         Objects.requireNonNull(selector, "selector is null");
         return RxJavaPlugins.onAssembly(new ObservableDematerialize<>(this, selector));
     }
@@ -8312,7 +8312,7 @@ public final Observable<T> distinct() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Observable<T> distinct(@NonNull Function<? super T, K> keySelector) {
+    public final <@NonNull K> Observable<T> distinct(@NonNull Function<? super T, K> keySelector) {
         return distinct(keySelector, Functions.createHashSet());
     }
 
@@ -8345,7 +8345,7 @@ public final <K> Observable<T> distinct(@NonNull Function<? super T, K> keySelec
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Observable<T> distinct(@NonNull Function<? super T, K> keySelector, @NonNull Supplier<? extends Collection<? super K>> collectionSupplier) {
+    public final <@NonNull K> Observable<T> distinct(@NonNull Function<? super T, K> keySelector, @NonNull Supplier<? extends Collection<? super K>> collectionSupplier) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         Objects.requireNonNull(collectionSupplier, "collectionSupplier is null");
         return RxJavaPlugins.onAssembly(new ObservableDistinct<>(this, keySelector, collectionSupplier));
@@ -8427,7 +8427,7 @@ public final Observable<T> distinctUntilChanged() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Observable<T> distinctUntilChanged(@NonNull Function<? super T, K> keySelector) {
+    public final <@NonNull K> Observable<T> distinctUntilChanged(@NonNull Function<? super T, K> keySelector) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         return RxJavaPlugins.onAssembly(new ObservableDistinctUntilChanged<>(this, keySelector, ObjectHelper.equalsPredicate()));
     }
@@ -9014,7 +9014,7 @@ public final Single<T> firstOrError() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return flatMap(mapper, false);
     }
 
@@ -9043,7 +9043,7 @@ public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends Ob
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, boolean delayErrors) {
+    public final <@NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, boolean delayErrors) {
         return flatMap(mapper, delayErrors, Integer.MAX_VALUE);
     }
 
@@ -9077,7 +9077,7 @@ public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends Ob
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
+    public final <@NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, boolean delayErrors, int maxConcurrency) {
         return flatMap(mapper, delayErrors, maxConcurrency, bufferSize());
     }
 
@@ -9113,7 +9113,7 @@ public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends Ob
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
+    public final <@NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper,
             boolean delayErrors, int maxConcurrency, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -9156,7 +9156,7 @@ public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends Ob
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(
+    public final <@NonNull R> Observable<R> flatMap(
             @NonNull Function<? super T, ? extends ObservableSource<? extends R>> onNextMapper,
             @NonNull Function<? super Throwable, ? extends ObservableSource<? extends R>> onErrorMapper,
             @NonNull Supplier<? extends ObservableSource<? extends R>> onCompleteSupplier) {
@@ -9198,7 +9198,7 @@ public final <R> Observable<R> flatMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(
+    public final <@NonNull R> Observable<R> flatMap(
             @NonNull Function<? super T, ? extends ObservableSource<? extends R>> onNextMapper,
             @NonNull Function<Throwable, ? extends ObservableSource<? extends R>> onErrorMapper,
             @NonNull Supplier<? extends ObservableSource<? extends R>> onCompleteSupplier,
@@ -9236,7 +9236,7 @@ public final <R> Observable<R> flatMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int maxConcurrency) {
+    public final <@NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int maxConcurrency) {
         return flatMap(mapper, false, maxConcurrency, bufferSize());
     }
 
@@ -9266,7 +9266,7 @@ public final <R> Observable<R> flatMap(@NonNull Function<? super T, ? extends Ob
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
         return flatMap(mapper, combiner, false, bufferSize(), bufferSize());
     }
@@ -9300,7 +9300,7 @@ public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors) {
         return flatMap(mapper, combiner, delayErrors, bufferSize(), bufferSize());
     }
@@ -9339,7 +9339,7 @@ public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors, int maxConcurrency) {
         return flatMap(mapper, combiner, delayErrors, maxConcurrency, bufferSize());
     }
@@ -9380,7 +9380,7 @@ public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, boolean delayErrors, int maxConcurrency, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -9418,7 +9418,7 @@ public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Observable<R> flatMap(@NonNull Function<? super T, ? extends ObservableSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner, int maxConcurrency) {
         return flatMap(mapper, combiner, false, maxConcurrency, bufferSize());
     }
@@ -9488,7 +9488,7 @@ public final Completable flatMapCompletable(@NonNull Function<? super T, ? exten
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<U> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Observable<U> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableFlattenIterable<>(this, mapper));
     }
@@ -9522,7 +9522,7 @@ public final <U> Observable<U> flatMapIterable(@NonNull Function<? super T, ? ex
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Observable<V> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper,
+    public final <@NonNull U, @NonNull V> Observable<V> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends V> combiner) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -9546,7 +9546,7 @@ public final <U, V> Observable<V> flatMapIterable(@NonNull Function<? super T, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return flatMapMaybe(mapper, false);
     }
 
@@ -9570,7 +9570,7 @@ public final <R> Observable<R> flatMapMaybe(@NonNull Function<? super T, ? exten
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean delayErrors) {
+    public final <@NonNull R> Observable<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper, boolean delayErrors) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableFlatMapMaybe<>(this, mapper, delayErrors));
     }
@@ -9592,7 +9592,7 @@ public final <R> Observable<R> flatMapMaybe(@NonNull Function<? super T, ? exten
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         return flatMapSingle(mapper, false);
     }
 
@@ -9616,7 +9616,7 @@ public final <R> Observable<R> flatMapSingle(@NonNull Function<? super T, ? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean delayErrors) {
+    public final <@NonNull R> Observable<R> flatMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper, boolean delayErrors) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableFlatMapSingle<>(this, mapper, delayErrors));
     }
@@ -9775,7 +9775,7 @@ public final Disposable forEachWhile(@NonNull Predicate<? super T> onNext, @NonN
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Observable<GroupedObservable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector) {
+    public final <@NonNull K> Observable<GroupedObservable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector) {
         return groupBy(keySelector, (Function)Functions.identity(), false, bufferSize());
     }
 
@@ -9820,7 +9820,7 @@ public final <K> Observable<GroupedObservable<K, T>> groupBy(@NonNull Function<?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Observable<GroupedObservable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector, boolean delayError) {
+    public final <@NonNull K> Observable<GroupedObservable<K, T>> groupBy(@NonNull Function<? super T, ? extends K> keySelector, boolean delayError) {
         return groupBy(keySelector, (Function)Functions.identity(), delayError, bufferSize());
     }
 
@@ -9865,7 +9865,7 @@ public final <K> Observable<GroupedObservable<K, T>> groupBy(@NonNull Function<?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             Function<? super T, ? extends V> valueSelector) {
         return groupBy(keySelector, valueSelector, false, bufferSize());
     }
@@ -9914,7 +9914,7 @@ public final <K, V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Functio
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector, boolean delayError) {
         return groupBy(keySelector, valueSelector, delayError, bufferSize());
     }
@@ -9966,7 +9966,7 @@ public final <K, V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Functio
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
+    public final <@NonNull K, @NonNull V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             boolean delayError, int bufferSize) {
         Objects.requireNonNull(keySelector, "keySelector is null");
@@ -10010,7 +10010,7 @@ public final <K, V> Observable<GroupedObservable<K, V>> groupBy(@NonNull Functio
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <TRight, TLeftEnd, TRightEnd, R> Observable<R> groupJoin(
+    public final <@NonNull TRight, @NonNull TLeftEnd, @NonNull TRightEnd, @NonNull R> Observable<R> groupJoin(
             @NonNull ObservableSource<? extends TRight> other,
             @NonNull Function<? super T, ? extends ObservableSource<TLeftEnd>> leftEnd,
             @NonNull Function<? super TRight, ? extends ObservableSource<TRightEnd>> rightEnd,
@@ -10122,7 +10122,7 @@ public final Single<Boolean> isEmpty() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <TRight, TLeftEnd, TRightEnd, R> Observable<R> join(
+    public final <@NonNull TRight, @NonNull TLeftEnd, @NonNull TRightEnd, @NonNull R> Observable<R> join(
             @NonNull ObservableSource<? extends TRight> other,
             @NonNull Function<? super T, ? extends ObservableSource<TLeftEnd>> leftEnd,
             @NonNull Function<? super TRight, ? extends ObservableSource<TRightEnd>> rightEnd,
@@ -10346,7 +10346,7 @@ public final Single<T> lastOrError() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> lift(@NonNull ObservableOperator<? extends R, ? super T> lifter) {
+    public final <@NonNull R> Observable<R> lift(@NonNull ObservableOperator<? extends R, ? super T> lifter) {
         Objects.requireNonNull(lifter, "lifter is null");
         return RxJavaPlugins.onAssembly(new ObservableLift<>(this, lifter));
     }
@@ -10636,7 +10636,7 @@ public final Observable<T> observeOn(@NonNull Scheduler scheduler, boolean delay
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<U> ofType(@NonNull Class<U> clazz) {
+    public final <@NonNull U> Observable<U> ofType(@NonNull Class<U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return filter(Functions.isInstanceOf(clazz)).cast(clazz);
     }
@@ -10893,7 +10893,7 @@ public final ConnectableObservable<T> publish() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> publish(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector) {
+    public final <@NonNull R> Observable<R> publish(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector) {
         Objects.requireNonNull(selector, "selector is null");
         return RxJavaPlugins.onAssembly(new ObservablePublishSelector<>(this, selector));
     }
@@ -11183,7 +11183,7 @@ public final ConnectableObservable<T> replay() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector) {
         Objects.requireNonNull(selector, "selector is null");
         return ObservableReplay.multicastSelector(ObservableInternalHelper.replaySupplier(this), selector);
     }
@@ -11218,7 +11218,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return ObservableReplay.multicastSelector(ObservableInternalHelper.replaySupplier(this, bufferSize, false), selector);
@@ -11256,7 +11256,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, boolean eagerTruncate) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, boolean eagerTruncate) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return ObservableReplay.multicastSelector(ObservableInternalHelper.replaySupplier(this, bufferSize, eagerTruncate), selector);
@@ -11295,7 +11295,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit) {
         return replay(selector, bufferSize, time, unit, Schedulers.computation());
     }
 
@@ -11337,7 +11337,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         Objects.requireNonNull(unit, "unit is null");
@@ -11385,7 +11385,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, int bufferSize, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
         Objects.requireNonNull(selector, "selector is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         Objects.requireNonNull(unit, "unit is null");
@@ -11421,7 +11421,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.COMPUTATION)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, @NonNull TimeUnit unit) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, @NonNull TimeUnit unit) {
         return replay(selector, time, unit, Schedulers.computation());
     }
 
@@ -11455,7 +11455,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
         Objects.requireNonNull(selector, "selector is null");
         Objects.requireNonNull(unit, "unit is null");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -11494,7 +11494,7 @@ public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ?
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.CUSTOM)
     @NonNull
-    public final <R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
+    public final <@NonNull R> Observable<R> replay(@NonNull Function<? super Observable<T>, ? extends ObservableSource<R>> selector, long time, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, boolean eagerTruncate) {
         Objects.requireNonNull(selector, "selector is null");
         Objects.requireNonNull(unit, "unit is null");
         Objects.requireNonNull(scheduler, "scheduler is null");
@@ -12192,7 +12192,7 @@ public final Observable<T> sample(long period, @NonNull TimeUnit unit, @NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> sample(@NonNull ObservableSource<U> sampler) {
+    public final <@NonNull U> Observable<T> sample(@NonNull ObservableSource<U> sampler) {
         Objects.requireNonNull(sampler, "sampler is null");
         return RxJavaPlugins.onAssembly(new ObservableSampleWithObservable<>(this, sampler, false));
     }
@@ -12225,7 +12225,7 @@ public final <U> Observable<T> sample(@NonNull ObservableSource<U> sampler) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> sample(@NonNull ObservableSource<U> sampler, boolean emitLast) {
+    public final <@NonNull U> Observable<T> sample(@NonNull ObservableSource<U> sampler, boolean emitLast) {
         Objects.requireNonNull(sampler, "sampler is null");
         return RxJavaPlugins.onAssembly(new ObservableSampleWithObservable<>(this, sampler, emitLast));
     }
@@ -12303,7 +12303,7 @@ public final Observable<T> scan(@NonNull BiFunction<T, T, T> accumulator) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> scan(@NonNull R initialValue, @NonNull BiFunction<R, ? super T, R> accumulator) {
+    public final <@NonNull R> Observable<R> scan(@NonNull R initialValue, @NonNull BiFunction<R, ? super T, R> accumulator) {
         Objects.requireNonNull(initialValue, "initialValue is null");
         return scanWith(Functions.justSupplier(initialValue), accumulator);
     }
@@ -12338,7 +12338,7 @@ public final <R> Observable<R> scan(@NonNull R initialValue, @NonNull BiFunction
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> scanWith(@NonNull Supplier<R> seedSupplier, @NonNull BiFunction<R, ? super T, R> accumulator) {
+    public final <@NonNull R> Observable<R> scanWith(@NonNull Supplier<R> seedSupplier, @NonNull BiFunction<R, ? super T, R> accumulator) {
         Objects.requireNonNull(seedSupplier, "seedSupplier is null");
         Objects.requireNonNull(accumulator, "accumulator is null");
         return RxJavaPlugins.onAssembly(new ObservableScanSeed<>(this, seedSupplier, accumulator));
@@ -12758,7 +12758,7 @@ public final Observable<T> skipLast(long time, @NonNull TimeUnit unit, @NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> skipUntil(@NonNull ObservableSource<U> other) {
+    public final <@NonNull U> Observable<T> skipUntil(@NonNull ObservableSource<U> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new ObservableSkipUntil<>(this, other));
     }
@@ -12862,7 +12862,7 @@ public final Observable<T> sorted(@NonNull Comparator<? super T> comparator) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Observable<T> startWithIterable(@NonNull Iterable<@NonNull ? extends T> items) {
+    public final Observable<T> startWithIterable(@NonNull Iterable<? extends T> items) {
         return concatArray(fromIterable(items), this);
     }
 
@@ -13305,7 +13305,7 @@ public final Observable<T> switchIfEmpty(@NonNull ObservableSource<? extends T>
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> switchMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return switchMap(mapper, bufferSize());
     }
 
@@ -13338,7 +13338,7 @@ public final <R> Observable<R> switchMap(@NonNull Function<? super T, ? extends
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Observable<R> switchMap(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         if (this instanceof ScalarSupplier) {
@@ -13472,7 +13472,7 @@ public final Completable switchMapCompletableDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> switchMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableSwitchMapMaybe<>(this, mapper, false));
     }
@@ -13500,7 +13500,7 @@ public final <R> Observable<R> switchMapMaybe(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> switchMapMaybeDelayError(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableSwitchMapMaybe<>(this, mapper, true));
     }
@@ -13532,7 +13532,7 @@ public final <R> Observable<R> switchMapMaybeDelayError(@NonNull Function<? supe
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> switchMapSingle(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableSwitchMapSingle<>(this, mapper, false));
     }
@@ -13565,7 +13565,7 @@ public final <R> Observable<R> switchMapSingle(@NonNull Function<? super T, ? ex
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> switchMapSingleDelayError(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableSwitchMapSingle<>(this, mapper, true));
     }
@@ -13598,7 +13598,7 @@ public final <R> Observable<R> switchMapSingleDelayError(@NonNull Function<? sup
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> switchMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper) {
         return switchMapDelayError(mapper, bufferSize());
     }
 
@@ -13633,7 +13633,7 @@ public final <R> Observable<R> switchMapDelayError(@NonNull Function<? super T,
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> switchMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
+    public final <@NonNull R> Observable<R> switchMapDelayError(@NonNull Function<? super T, ? extends ObservableSource<? extends R>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         if (this instanceof ScalarSupplier) {
@@ -14048,7 +14048,7 @@ public final Observable<T> takeLast(long time, @NonNull TimeUnit unit, @NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> Observable<T> takeUntil(@NonNull ObservableSource<U> other) {
+    public final <@NonNull U> Observable<T> takeUntil(@NonNull ObservableSource<U> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new ObservableTakeUntil<>(this, other));
     }
@@ -14556,7 +14556,7 @@ public final Observable<Timed<T>> timeInterval(@NonNull TimeUnit unit, @NonNull
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <V> Observable<T> timeout(@NonNull Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator) {
+    public final <@NonNull V> Observable<T> timeout(@NonNull Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator) {
         return timeout0(null, itemTimeoutIndicator, null);
     }
 
@@ -14588,7 +14588,7 @@ public final <V> Observable<T> timeout(@NonNull Function<? super T, ? extends Ob
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <V> Observable<T> timeout(@NonNull Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator,
+    public final <@NonNull V> Observable<T> timeout(@NonNull Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator,
             @NonNull ObservableSource<? extends T> fallback) {
         Objects.requireNonNull(fallback, "fallback is null");
         return timeout0(null, itemTimeoutIndicator, fallback);
@@ -14740,7 +14740,7 @@ public final Observable<T> timeout(long timeout, @NonNull TimeUnit unit, @NonNul
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Observable<T> timeout(@NonNull ObservableSource<U> firstTimeoutIndicator,
+    public final <@NonNull U, @NonNull V> Observable<T> timeout(@NonNull ObservableSource<U> firstTimeoutIndicator,
             @NonNull Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator) {
         Objects.requireNonNull(firstTimeoutIndicator, "firstTimeoutIndicator is null");
         return timeout0(firstTimeoutIndicator, itemTimeoutIndicator, null);
@@ -14778,7 +14778,7 @@ public final <U, V> Observable<T> timeout(@NonNull ObservableSource<U> firstTime
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Observable<T> timeout(
+    public final <@NonNull U, @NonNull V> Observable<T> timeout(
             @NonNull ObservableSource<U> firstTimeoutIndicator,
             @NonNull Function<? super T, ? extends ObservableSource<V>> itemTimeoutIndicator,
             @NonNull ObservableSource<? extends T> fallback) {
@@ -14918,7 +14918,7 @@ public final Observable<Timed<T>> timestamp(@NonNull TimeUnit unit, @NonNull Sch
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> R to(@NonNull ObservableConverter<T, ? extends R> converter) {
+    public final <@NonNull R> R to(@NonNull ObservableConverter<T, ? extends R> converter) {
         return Objects.requireNonNull(converter, "converter is null").apply(this);
     }
 
@@ -15048,7 +15048,7 @@ public final <R> R to(@NonNull ObservableConverter<T, ? extends R> converter) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Single<@NonNull Map<K, T>> toMap(@NonNull Function<? super T, ? extends K> keySelector) {
+    public final <@NonNull K> Single<@NonNull Map<K, T>> toMap(@NonNull Function<? super T, ? extends K> keySelector) {
         Objects.requireNonNull(keySelector, "keySelector is null");
         return collect(HashMapSupplier.asSupplier(), Functions.toMapKeySelector(keySelector));
     }
@@ -15083,7 +15083,7 @@ public final <R> R to(@NonNull ObservableConverter<T, ? extends R> converter) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<Map<K, V>> toMap(
+    public final <@NonNull K, @NonNull V> Single<Map<K, V>> toMap(
             @NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector) {
         Objects.requireNonNull(keySelector, "keySelector is null");
@@ -15120,7 +15120,7 @@ public final <K, V> Single<Map<K, V>> toMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<Map<K, V>> toMap(
+    public final <@NonNull K, @NonNull V> Single<Map<K, V>> toMap(
             @NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             @NonNull Supplier<? extends Map<K, V>> mapSupplier) {
@@ -15154,7 +15154,7 @@ public final <K, V> Single<Map<K, V>> toMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K> Single<@NonNull Map<K, Collection<T>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector) {
+    public final <@NonNull K> Single<@NonNull Map<K, Collection<T>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector) {
         Function<? super T, ? extends T> valueSelector = Functions.identity();
         Supplier<Map<K, Collection<T>>> mapSupplier = HashMapSupplier.asSupplier();
         Function<K, List<T>> collectionFactory = ArrayListSupplier.asFunction();
@@ -15189,7 +15189,7 @@ public final <K, V> Single<Map<K, V>> toMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<@NonNull Map<K, Collection<V>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector, Function<? super T, ? extends V> valueSelector) {
+    public final <@NonNull K, @NonNull V> Single<@NonNull Map<K, Collection<V>>> toMultimap(@NonNull Function<? super T, ? extends K> keySelector, Function<? super T, ? extends V> valueSelector) {
         Supplier<Map<K, Collection<V>>> mapSupplier = HashMapSupplier.asSupplier();
         Function<K, List<V>> collectionFactory = ArrayListSupplier.asFunction();
         return toMultimap(keySelector, valueSelector, mapSupplier, collectionFactory);
@@ -15227,7 +15227,7 @@ public final <K, V> Single<Map<K, V>> toMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<@NonNull Map<K, Collection<V>>> toMultimap(
+    public final <@NonNull K, @NonNull V> Single<@NonNull Map<K, Collection<V>>> toMultimap(
             @NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             @NonNull Supplier<? extends Map<K, Collection<V>>> mapSupplier,
@@ -15269,7 +15269,7 @@ public final <K, V> Single<Map<K, V>> toMap(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <K, V> Single<@NonNull Map<K, Collection<V>>> toMultimap(
+    public final <@NonNull K, @NonNull V> Single<@NonNull Map<K, Collection<V>>> toMultimap(
             @NonNull Function<? super T, ? extends K> keySelector,
             @NonNull Function<? super T, ? extends V> valueSelector,
             @NonNull Supplier<Map<K, Collection<V>>> mapSupplier
@@ -15996,7 +15996,7 @@ public final Observable<Observable<T>> window(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Observable<Observable<T>> window(@NonNull ObservableSource<B> boundaryIndicator) {
+    public final <@NonNull B> Observable<Observable<T>> window(@NonNull ObservableSource<B> boundaryIndicator) {
         return window(boundaryIndicator, bufferSize());
     }
 
@@ -16030,7 +16030,7 @@ public final <B> Observable<Observable<T>> window(@NonNull ObservableSource<B> b
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <B> Observable<Observable<T>> window(@NonNull ObservableSource<B> boundaryIndicator, int bufferSize) {
+    public final <@NonNull B> Observable<Observable<T>> window(@NonNull ObservableSource<B> boundaryIndicator, int bufferSize) {
         Objects.requireNonNull(boundaryIndicator, "boundaryIndicator is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ObservableWindowBoundary<>(this, boundaryIndicator, bufferSize));
@@ -16067,7 +16067,7 @@ public final <B> Observable<Observable<T>> window(@NonNull ObservableSource<B> b
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Observable<Observable<T>> window(
+    public final <@NonNull U, @NonNull V> Observable<Observable<T>> window(
             @NonNull ObservableSource<U> openingIndicator,
             @NonNull Function<? super U, ? extends ObservableSource<V>> closingIndicator) {
         return window(openingIndicator, closingIndicator, bufferSize());
@@ -16107,7 +16107,7 @@ public final <U, V> Observable<Observable<T>> window(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, V> Observable<Observable<T>> window(
+    public final <@NonNull U, @NonNull V> Observable<Observable<T>> window(
             @NonNull ObservableSource<U> openingIndicator,
             @NonNull Function<? super U, ? extends ObservableSource<V>> closingIndicator, int bufferSize) {
         Objects.requireNonNull(openingIndicator, "openingIndicator is null");
@@ -16149,7 +16149,7 @@ public final <U, V> Observable<Observable<T>> window(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> withLatestFrom(@NonNull ObservableSource<? extends U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
+    public final <@NonNull U, @NonNull R> Observable<R> withLatestFrom(@NonNull ObservableSource<? extends U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
         Objects.requireNonNull(other, "other is null");
         Objects.requireNonNull(combiner, "combiner is null");
 
@@ -16186,7 +16186,7 @@ public final <U, R> Observable<R> withLatestFrom(@NonNull ObservableSource<? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T1, T2, R> Observable<R> withLatestFrom(
+    public final <@NonNull T1, @NonNull T2, @NonNull R> Observable<R> withLatestFrom(
             @NonNull ObservableSource<T1> source1, @NonNull ObservableSource<T2> source2,
             @NonNull Function3<? super T, ? super T1, ? super T2, R> combiner) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -16228,7 +16228,7 @@ public final <T1, T2, R> Observable<R> withLatestFrom(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T1, T2, T3, R> Observable<R> withLatestFrom(
+    public final <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Observable<R> withLatestFrom(
             @NonNull ObservableSource<T1> source1, @NonNull ObservableSource<T2> source2,
             @NonNull ObservableSource<T3> source3,
             @NonNull Function4<? super T, ? super T1, ? super T2, ? super T3, R> combiner) {
@@ -16275,7 +16275,7 @@ public final <T1, T2, T3, R> Observable<R> withLatestFrom(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <T1, T2, T3, T4, R> Observable<R> withLatestFrom(
+    public final <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Observable<R> withLatestFrom(
             @NonNull ObservableSource<T1> source1, @NonNull ObservableSource<T2> source2,
             @NonNull ObservableSource<T3> source3, @NonNull ObservableSource<T4> source4,
             @NonNull Function5<? super T, ? super T1, ? super T2, ? super T3, ? super T4, R> combiner) {
@@ -16315,7 +16315,7 @@ public final <T1, T2, T3, T4, R> Observable<R> withLatestFrom(
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> withLatestFrom(@NonNull ObservableSource<?>[] others, @NonNull Function<? super Object[], R> combiner) {
+    public final <@NonNull R> Observable<R> withLatestFrom(@NonNull ObservableSource<?>[] others, @NonNull Function<? super Object[], R> combiner) {
         Objects.requireNonNull(others, "others is null");
         Objects.requireNonNull(combiner, "combiner is null");
         return RxJavaPlugins.onAssembly(new ObservableWithLatestFromMany<>(this, others, combiner));
@@ -16348,7 +16348,7 @@ public final <R> Observable<R> withLatestFrom(@NonNull ObservableSource<?>[] oth
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> withLatestFrom(@NonNull Iterable<@NonNull ? extends ObservableSource<?>> others, @NonNull Function<? super Object[], R> combiner) {
+    public final <@NonNull R> Observable<R> withLatestFrom(@NonNull Iterable<@NonNull ? extends ObservableSource<?>> others, @NonNull Function<? super Object[], R> combiner) {
         Objects.requireNonNull(others, "others is null");
         Objects.requireNonNull(combiner, "combiner is null");
         return RxJavaPlugins.onAssembly(new ObservableWithLatestFromMany<>(this, others, combiner));
@@ -16383,7 +16383,7 @@ public final <R> Observable<R> withLatestFrom(@NonNull Iterable<@NonNull ? exten
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull U, R> Observable<R> zipWith(@NonNull Iterable<U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
+    public final <@NonNull U, @NonNull R> Observable<R> zipWith(@NonNull Iterable<U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
         Objects.requireNonNull(other, "other is null");
         Objects.requireNonNull(zipper, "zipper is null");
         return RxJavaPlugins.onAssembly(new ObservableZipIterable<>(this, other, zipper));
@@ -16427,7 +16427,7 @@ public final <R> Observable<R> withLatestFrom(@NonNull Iterable<@NonNull ? exten
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> zipWith(@NonNull ObservableSource<? extends U> other,
+    public final <@NonNull U, @NonNull R> Observable<R> zipWith(@NonNull ObservableSource<? extends U> other,
             @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
         Objects.requireNonNull(other, "other is null");
         return zip(this, other, zipper);
@@ -16474,7 +16474,7 @@ public final <U, R> Observable<R> zipWith(@NonNull ObservableSource<? extends U>
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> zipWith(@NonNull ObservableSource<? extends U> other,
+    public final <@NonNull U, @NonNull R> Observable<R> zipWith(@NonNull ObservableSource<? extends U> other,
             @NonNull BiFunction<? super T, ? super U, ? extends R> zipper, boolean delayError) {
         return zip(this, other, zipper, delayError);
     }
@@ -16523,7 +16523,7 @@ public final <U, R> Observable<R> zipWith(@NonNull ObservableSource<? extends U>
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Observable<R> zipWith(@NonNull ObservableSource<? extends U> other,
+    public final <@NonNull U, @NonNull R> Observable<R> zipWith(@NonNull ObservableSource<? extends U> other,
             @NonNull BiFunction<? super T, ? super U, ? extends R> zipper, boolean delayError, int bufferSize) {
         return zip(this, other, zipper, delayError, bufferSize);
     }
@@ -16605,7 +16605,7 @@ public final TestObserver<T> test(boolean dispose) { // NoPMD
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<@NonNull T> fromOptional(@NonNull Optional<T> optional) {
+    public static <@NonNull T> Observable<@NonNull T> fromOptional(@NonNull Optional<T> optional) {
         Objects.requireNonNull(optional, "optional is null");
         return optional.map(Observable::just).orElseGet(Observable::empty);
     }
@@ -16639,7 +16639,7 @@ public final TestObserver<T> test(boolean dispose) { // NoPMD
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
+    public static <@NonNull T> Observable<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
         Objects.requireNonNull(stage, "stage is null");
         return RxJavaPlugins.onAssembly(new ObservableFromCompletionStage<>(stage));
     }
@@ -16682,7 +16682,7 @@ public final TestObserver<T> test(boolean dispose) { // NoPMD
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Observable<@NonNull T> fromStream(@NonNull Stream<T> stream) {
+    public static <@NonNull T> Observable<@NonNull T> fromStream(@NonNull Stream<T> stream) {
         Objects.requireNonNull(stream, "stream is null");
         return RxJavaPlugins.onAssembly(new ObservableFromStream<>(stream));
     }
@@ -16736,7 +16736,7 @@ public final TestObserver<T> test(boolean dispose) { // NoPMD
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R, A> Single<R> collect(@NonNull Collector<? super T, A, R> collector) {
+    public final <@NonNull R, @NonNull A> Single<R> collect(@NonNull Collector<? super T, A, R> collector) {
         Objects.requireNonNull(collector, "collector is null");
         return RxJavaPlugins.onAssembly(new ObservableCollectWithCollectorSingle<>(this, collector));
     }
@@ -17034,7 +17034,7 @@ public final Stream<T> blockingStream(int capacityHint) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> Observable<R> concatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> concatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         return flatMapStream(mapper);
     }
 
@@ -17081,7 +17081,7 @@ public final Stream<T> blockingStream(int capacityHint) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> Observable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ObservableFlatMapStream<>(this, mapper));
     }
diff --git a/src/main/java/io/reactivex/rxjava3/core/Single.java b/src/main/java/io/reactivex/rxjava3/core/Single.java
index 66e1ffd3d5..eb590aa428 100644
--- a/src/main/java/io/reactivex/rxjava3/core/Single.java
+++ b/src/main/java/io/reactivex/rxjava3/core/Single.java
@@ -134,7 +134,7 @@ public abstract class Single<@NonNull T> implements SingleSource<T> {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> amb(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Single<T> amb(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new SingleAmb<>(null, sources));
     }
@@ -159,7 +159,7 @@ public static <T> Single<T> amb(@NonNull Iterable<@NonNull ? extends SingleSourc
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Single<T> ambArray(@NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Single<T> ambArray(@NonNull SingleSource<? extends T>... sources) {
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
             return error(SingleInternalHelper.emptyThrower());
@@ -193,7 +193,7 @@ public static <T> Single<T> ambArray(@NonNull SingleSource<? extends T>... sourc
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapSingleDelayError(Functions.identity(), false);
     }
 
@@ -215,7 +215,7 @@ public static <T> Flowable<T> concat(@NonNull Iterable<@NonNull ? extends Single
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Observable<T> concat(@NonNull ObservableSource<? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Observable<T> concat(@NonNull ObservableSource<? extends SingleSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new ObservableConcatMapSingle<>(sources, Functions.identity(), ErrorMode.IMMEDIATE, 2));
     }
@@ -242,7 +242,7 @@ public static <T> Observable<T> concat(@NonNull ObservableSource<? extends Singl
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         return concat(sources, 2);
     }
 
@@ -270,7 +270,7 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Singl
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int prefetch) {
+    public static <@NonNull T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int prefetch) {
         Objects.requireNonNull(sources, "sources is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new FlowableConcatMapSinglePublisher<>(sources, Functions.identity(), ErrorMode.IMMEDIATE, prefetch));
@@ -300,7 +300,7 @@ public static <T> Flowable<T> concat(@NonNull Publisher<@NonNull ? extends Singl
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
+    public static <@NonNull T> Flowable<T> concat(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2
      ) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -334,7 +334,7 @@ public static <T> Flowable<T> concat(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
+    public static <@NonNull T> Flowable<T> concat(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2,
             @NonNull SingleSource<? extends T> source3
      ) {
@@ -372,7 +372,7 @@ public static <T> Flowable<T> concat(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concat(
+    public static <@NonNull T> Flowable<T> concat(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2,
             @NonNull SingleSource<? extends T> source3, @NonNull SingleSource<? extends T> source4
      ) {
@@ -405,7 +405,7 @@ public static <T> Flowable<T> concat(
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> concatArray(@NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArray(@NonNull SingleSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapSingleDelayError(Functions.identity(), false);
     }
 
@@ -431,7 +431,7 @@ public static <T> Flowable<T> concatArray(@NonNull SingleSource<? extends T>...
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> concatArrayDelayError(@NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayDelayError(@NonNull SingleSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapSingleDelayError(Functions.identity(), true);
     }
 
@@ -459,7 +459,7 @@ public static <T> Flowable<T> concatArrayDelayError(@NonNull SingleSource<? exte
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> concatArrayEager(@NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEager(@NonNull SingleSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapEager(SingleInternalHelper.toFlowable());
     }
 
@@ -488,7 +488,7 @@ public static <T> Flowable<T> concatArrayEager(@NonNull SingleSource<? extends T
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> concatArrayEagerDelayError(@NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> concatArrayEagerDelayError(@NonNull SingleSource<? extends T>... sources) {
         return Flowable.fromArray(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), true);
     }
 
@@ -515,7 +515,7 @@ public static <T> Flowable<T> concatArrayEagerDelayError(@NonNull SingleSource<?
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapSingleDelayError(Functions.identity());
     }
 
@@ -542,7 +542,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Iterable<@NonNull ? exte
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapSingleDelayError(Functions.identity());
     }
 
@@ -574,7 +574,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? ext
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int prefetch) {
+    public static <@NonNull T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int prefetch) {
         return Flowable.fromPublisher(sources).concatMapSingleDelayError(Functions.identity(), true, prefetch);
     }
 
@@ -601,7 +601,7 @@ public static <T> Flowable<T> concatDelayError(@NonNull Publisher<@NonNull ? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), false);
     }
 
@@ -633,7 +633,7 @@ public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends S
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), false, maxConcurrency, 1);
     }
 
@@ -662,7 +662,7 @@ public static <T> Flowable<T> concatEager(@NonNull Iterable<@NonNull ? extends S
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapEager(SingleInternalHelper.toFlowable());
     }
 
@@ -696,7 +696,7 @@ public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromPublisher(sources).concatMapEager(SingleInternalHelper.toFlowable(), maxConcurrency, 1);
     }
 
@@ -725,7 +725,7 @@ public static <T> Flowable<T> concatEager(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), true);
     }
 
@@ -757,7 +757,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ?
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromIterable(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), true, maxConcurrency, 1);
     }
 
@@ -788,7 +788,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Iterable<@NonNull ?
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromPublisher(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), true);
     }
 
@@ -822,7 +822,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
+    public static <@NonNull T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources, int maxConcurrency) {
         return Flowable.fromPublisher(sources).concatMapEagerDelayError(SingleInternalHelper.toFlowable(), true, maxConcurrency, 1);
     }
 
@@ -895,7 +895,7 @@ public static <T> Flowable<T> concatEagerDelayError(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> defer(@NonNull Supplier<? extends SingleSource<? extends T>> supplier) {
+    public static <@NonNull T> Single<T> defer(@NonNull Supplier<? extends SingleSource<? extends T>> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new SingleDefer<>(supplier));
     }
@@ -917,7 +917,7 @@ public static <T> Single<T> defer(@NonNull Supplier<? extends SingleSource<? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> error(@NonNull Supplier<? extends Throwable> supplier) {
+    public static <@NonNull T> Single<T> error(@NonNull Supplier<? extends Throwable> supplier) {
         Objects.requireNonNull(supplier, "supplier is null");
         return RxJavaPlugins.onAssembly(new SingleError<>(supplier));
     }
@@ -944,7 +944,7 @@ public static <T> Single<T> error(@NonNull Supplier<? extends Throwable> supplie
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> error(@NonNull Throwable throwable) {
+    public static <@NonNull T> Single<T> error(@NonNull Throwable throwable) {
         Objects.requireNonNull(throwable, "throwable is null");
         return error(Functions.justSupplier(throwable));
     }
@@ -1080,7 +1080,7 @@ public static <T> Single<T> error(@NonNull Throwable throwable) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
+    public static <@NonNull T> Single<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
         Objects.requireNonNull(maybe, "maybe is null");
         return RxJavaPlugins.onAssembly(new MaybeToSingle<>(maybe, null));
     }
@@ -1105,7 +1105,7 @@ public static <T> Single<T> fromMaybe(@NonNull MaybeSource<T> maybe) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> fromMaybe(@NonNull MaybeSource<T> maybe, @NonNull T defaultItem) {
+    public static <@NonNull T> Single<T> fromMaybe(@NonNull MaybeSource<T> maybe, @NonNull T defaultItem) {
         Objects.requireNonNull(maybe, "maybe is null");
         Objects.requireNonNull(defaultItem, "defaultItem is null");
         return RxJavaPlugins.onAssembly(new MaybeToSingle<>(maybe, defaultItem));
@@ -1146,7 +1146,7 @@ public static <T> Single<T> fromMaybe(@NonNull MaybeSource<T> maybe, @NonNull T
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> fromPublisher(@NonNull Publisher<@NonNull ? extends T> publisher) {
+    public static <@NonNull T> Single<T> fromPublisher(@NonNull Publisher<? extends T> publisher) {
         Objects.requireNonNull(publisher, "publisher is null");
         return RxJavaPlugins.onAssembly(new SingleFromPublisher<>(publisher));
     }
@@ -1172,7 +1172,7 @@ public static <T> Single<T> fromPublisher(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> fromObservable(@NonNull ObservableSource<? extends T> observable) {
+    public static <@NonNull T> Single<T> fromObservable(@NonNull ObservableSource<? extends T> observable) {
         Objects.requireNonNull(observable, "observable is null");
         return RxJavaPlugins.onAssembly(new ObservableSingleSingle<>(observable, null));
     }
@@ -1279,7 +1279,7 @@ public static <T> Single<T> fromObservable(@NonNull ObservableSource<? extends T
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).flatMapSingle(Functions.identity());
     }
 
@@ -1318,7 +1318,7 @@ public static <T> Flowable<T> merge(@NonNull Iterable<@NonNull ? extends SingleS
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapSinglePublisher<>(sources, Functions.identity(), false, Integer.MAX_VALUE));
     }
@@ -1349,7 +1349,7 @@ public static <T> Flowable<T> merge(@NonNull Publisher<@NonNull ? extends Single
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> merge(@NonNull SingleSource<? extends SingleSource<? extends T>> source) {
+    public static <@NonNull T> Single<T> merge(@NonNull SingleSource<? extends SingleSource<? extends T>> source) {
         Objects.requireNonNull(source, "source is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMap<SingleSource<? extends T>, T>(source, Functions.identity()));
     }
@@ -1395,7 +1395,7 @@ public static <T> Single<T> merge(@NonNull SingleSource<? extends SingleSource<?
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
+    public static <@NonNull T> Flowable<T> merge(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2
      ) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -1446,7 +1446,7 @@ public static <T> Flowable<T> merge(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
+    public static <@NonNull T> Flowable<T> merge(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2,
             @NonNull SingleSource<? extends T> source3
      ) {
@@ -1501,7 +1501,7 @@ public static <T> Flowable<T> merge(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> merge(
+    public static <@NonNull T> Flowable<T> merge(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2,
             @NonNull SingleSource<? extends T> source3, @NonNull SingleSource<? extends T> source4
      ) {
@@ -1547,7 +1547,7 @@ public static <T> Flowable<T> merge(
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T> Flowable<T> mergeArray(SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArray(SingleSource<? extends T>... sources) {
         return Flowable.fromArray(sources).flatMapSingle(Functions.identity(), false, Math.max(1, sources.length));
     }
 
@@ -1583,7 +1583,7 @@ public static <T> Flowable<T> mergeArray(SingleSource<? extends T>... sources) {
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
     @NonNull
-    public static <T> Flowable<T> mergeArrayDelayError(@NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T> Flowable<T> mergeArrayDelayError(@NonNull SingleSource<? extends T>... sources) {
         return Flowable.fromArray(sources).flatMapSingle(Functions.identity(), true, Math.max(1, sources.length));
     }
 
@@ -1610,7 +1610,7 @@ public static <T> Flowable<T> mergeArrayDelayError(@NonNull SingleSource<? exten
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources) {
         return Flowable.fromIterable(sources).flatMapSingle(Functions.identity(), true, Integer.MAX_VALUE);
     }
 
@@ -1637,7 +1637,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Iterable<@NonNull ? exten
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableFlatMapSinglePublisher<>(sources, Functions.identity(), true, Integer.MAX_VALUE));
     }
@@ -1672,7 +1672,7 @@ public static <T> Flowable<T> mergeDelayError(@NonNull Publisher<@NonNull ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(
+    public static <@NonNull T> Flowable<T> mergeDelayError(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2
      ) {
         Objects.requireNonNull(source1, "source1 is null");
@@ -1712,7 +1712,7 @@ public static <T> Flowable<T> mergeDelayError(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(
+    public static <@NonNull T> Flowable<T> mergeDelayError(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2,
             @NonNull SingleSource<? extends T> source3
      ) {
@@ -1756,7 +1756,7 @@ public static <T> Flowable<T> mergeDelayError(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> mergeDelayError(
+    public static <@NonNull T> Flowable<T> mergeDelayError(
             @NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2,
             @NonNull SingleSource<? extends T> source3, @NonNull SingleSource<? extends T> source4
      ) {
@@ -1783,7 +1783,7 @@ public static <T> Flowable<T> mergeDelayError(
     @SchedulerSupport(SchedulerSupport.NONE)
     @SuppressWarnings("unchecked")
     @NonNull
-    public static <T> Single<T> never() {
+    public static <@NonNull T> Single<T> never() {
         return RxJavaPlugins.onAssembly((Single<T>) SingleNever.INSTANCE);
     }
 
@@ -1853,7 +1853,7 @@ public static Single<Long> timer(long delay, @NonNull TimeUnit unit, @NonNull Sc
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<Boolean> sequenceEqual(@NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2) { // NOPMD
+    public static <@NonNull T> Single<Boolean> sequenceEqual(@NonNull SingleSource<? extends T> source1, @NonNull SingleSource<? extends T> source2) { // NOPMD
         Objects.requireNonNull(source1, "source1 is null");
         Objects.requireNonNull(source2, "source2 is null");
         return RxJavaPlugins.onAssembly(new SingleEquals<>(source1, source2));
@@ -1888,7 +1888,7 @@ public static <T> Single<Boolean> sequenceEqual(@NonNull SingleSource<? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapSinglePublisher<>(sources, Functions.identity(), false));
     }
@@ -1923,7 +1923,7 @@ public static <T> Flowable<T> switchOnNext(@NonNull Publisher<@NonNull ? extends
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
+    public static <@NonNull T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull ? extends SingleSource<? extends T>> sources) {
         Objects.requireNonNull(sources, "sources is null");
         return RxJavaPlugins.onAssembly(new FlowableSwitchMapSinglePublisher<>(sources, Functions.identity(), true));
     }
@@ -1949,7 +1949,7 @@ public static <T> Flowable<T> switchOnNextDelayError(@NonNull Publisher<@NonNull
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> unsafeCreate(@NonNull SingleSource<T> onSubscribe) {
+    public static <@NonNull T> Single<T> unsafeCreate(@NonNull SingleSource<T> onSubscribe) {
         Objects.requireNonNull(onSubscribe, "onSubscribe is null");
         if (onSubscribe instanceof Single) {
             throw new IllegalArgumentException("unsafeCreate(Single) should be upgraded");
@@ -1982,7 +1982,7 @@ public static <T> Single<T> unsafeCreate(@NonNull SingleSource<T> onSubscribe) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T, U> Single<T> using(@NonNull Supplier<U> resourceSupplier,
+    public static <@NonNull T, @NonNull U> Single<T> using(@NonNull Supplier<U> resourceSupplier,
             @NonNull Function<? super U, ? extends SingleSource<? extends T>> sourceSupplier,
             @NonNull Consumer<? super U> resourceCleanup) {
         return using(resourceSupplier, sourceSupplier, resourceCleanup, true);
@@ -2018,7 +2018,7 @@ public static <T, U> Single<T> using(@NonNull Supplier<U> resourceSupplier,
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, U> Single<T> using(
+    public static <@NonNull T, @NonNull U> Single<T> using(
             @NonNull Supplier<U> resourceSupplier,
             @NonNull Function<? super U, ? extends SingleSource<? extends T>> sourceSupplier,
             @NonNull Consumer<? super U> resourceCleanup,
@@ -2047,7 +2047,7 @@ public static <T, U> Single<T> using(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T> Single<T> wrap(@NonNull SingleSource<T> source) {
+    public static <@NonNull T> Single<T> wrap(@NonNull SingleSource<T> source) {
         Objects.requireNonNull(source, "source is null");
         if (source instanceof Single) {
             return RxJavaPlugins.onAssembly((Single<T>)source);
@@ -2088,7 +2088,7 @@ public static <T> Single<T> wrap(@NonNull SingleSource<T> source) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T, R> Single<R> zip(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources,
+    public static <@NonNull T, @NonNull R> Single<R> zip(@NonNull Iterable<@NonNull ? extends SingleSource<? extends T>> sources,
             @NonNull Function<? super Object[], ? extends R> zipper) {
         Objects.requireNonNull(zipper, "zipper is null");
         Objects.requireNonNull(sources, "sources is null");
@@ -2122,7 +2122,7 @@ public static <T, R> Single<R> zip(@NonNull Iterable<@NonNull ? extends SingleSo
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull BiFunction<? super T1, ? super T2, ? extends R> zipper
      ) {
@@ -2162,7 +2162,7 @@ public static <T1, T2, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3,
             @NonNull Function3<? super T1, ? super T2, ? super T3, ? extends R> zipper
@@ -2207,7 +2207,7 @@ public static <T1, T2, T3, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3, @NonNull SingleSource<? extends T4> source4,
             @NonNull Function4<? super T1, ? super T2, ? super T3, ? super T4, ? extends R> zipper
@@ -2257,7 +2257,7 @@ public static <T1, T2, T3, T4, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3, @NonNull SingleSource<? extends T4> source4,
             @NonNull SingleSource<? extends T5> source5,
@@ -2312,7 +2312,7 @@ public static <T1, T2, T3, T4, T5, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3, @NonNull SingleSource<? extends T4> source4,
             @NonNull SingleSource<? extends T5> source5, @NonNull SingleSource<? extends T6> source6,
@@ -2371,7 +2371,7 @@ public static <T1, T2, T3, T4, T5, T6, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3, @NonNull SingleSource<? extends T4> source4,
             @NonNull SingleSource<? extends T5> source5, @NonNull SingleSource<? extends T6> source6,
@@ -2435,7 +2435,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3, @NonNull SingleSource<? extends T4> source4,
             @NonNull SingleSource<? extends T5> source5, @NonNull SingleSource<? extends T6> source6,
@@ -2504,7 +2504,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, R> Single<R> zip(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Single<R> zip(
+    public static <@NonNull T1, @NonNull T2, @NonNull T3, @NonNull T4, @NonNull T5, @NonNull T6, @NonNull T7, @NonNull T8, @NonNull T9, @NonNull R> Single<R> zip(
             @NonNull SingleSource<? extends T1> source1, @NonNull SingleSource<? extends T2> source2,
             @NonNull SingleSource<? extends T3> source3, @NonNull SingleSource<? extends T4> source4,
             @NonNull SingleSource<? extends T5> source5, @NonNull SingleSource<? extends T6> source6,
@@ -2558,7 +2558,7 @@ public static <T1, T2, T3, T4, T5, T6, T7, T8, T9, R> Single<R> zip(
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @SafeVarargs
-    public static <T, R> Single<R> zipArray(@NonNull Function<? super Object[], ? extends R> zipper, @NonNull SingleSource<? extends T>... sources) {
+    public static <@NonNull T, @NonNull R> Single<R> zipArray(@NonNull Function<? super Object[], ? extends R> zipper, @NonNull SingleSource<? extends T>... sources) {
         Objects.requireNonNull(zipper, "zipper is null");
         Objects.requireNonNull(sources, "sources is null");
         if (sources.length == 0) {
@@ -2633,7 +2633,7 @@ public final Single<T> hide() {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Single<R> compose(@NonNull SingleTransformer<? super T, ? extends R> transformer) {
+    public final <@NonNull R> Single<R> compose(@NonNull SingleTransformer<? super T, ? extends R> transformer) {
         return wrap(((SingleTransformer<T, R>) Objects.requireNonNull(transformer, "transformer is null")).apply(this));
     }
 
@@ -2676,7 +2676,7 @@ public final Single<T> cache() {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Single<U> cast(@NonNull Class<? extends U> clazz) {
+    public final <@NonNull U> Single<U> cast(@NonNull Class<? extends U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return map(Functions.castFunction(clazz));
     }
@@ -2704,7 +2704,7 @@ public final <U> Single<U> cast(@NonNull Class<? extends U> clazz) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Single<R> concatMap(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Single<R> concatMap(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMap<>(this, mapper));
     }
@@ -2759,7 +2759,7 @@ public final Completable concatMapCompletable(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Maybe<R> concatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         return flatMapMaybe(mapper);
     }
 
@@ -2938,7 +2938,7 @@ public final Single<T> delaySubscription(@NonNull CompletableSource subscription
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Single<T> delaySubscription(@NonNull SingleSource<U> subscriptionIndicator) {
+    public final <@NonNull U> Single<T> delaySubscription(@NonNull SingleSource<U> subscriptionIndicator) {
         Objects.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
         return RxJavaPlugins.onAssembly(new SingleDelayWithSingle<>(this, subscriptionIndicator));
     }
@@ -2964,7 +2964,7 @@ public final <U> Single<T> delaySubscription(@NonNull SingleSource<U> subscripti
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Single<T> delaySubscription(@NonNull ObservableSource<U> subscriptionIndicator) {
+    public final <@NonNull U> Single<T> delaySubscription(@NonNull ObservableSource<U> subscriptionIndicator) {
         Objects.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
         return RxJavaPlugins.onAssembly(new SingleDelayWithObservable<>(this, subscriptionIndicator));
     }
@@ -2995,7 +2995,7 @@ public final <U> Single<T> delaySubscription(@NonNull ObservableSource<U> subscr
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Single<T> delaySubscription(@NonNull Publisher<U> subscriptionIndicator) {
+    public final <@NonNull U> Single<T> delaySubscription(@NonNull Publisher<U> subscriptionIndicator) {
         Objects.requireNonNull(subscriptionIndicator, "subscriptionIndicator is null");
         return RxJavaPlugins.onAssembly(new SingleDelayWithPublisher<>(this, subscriptionIndicator));
     }
@@ -3385,7 +3385,7 @@ public final Maybe<T> filter(@NonNull Predicate<? super T> predicate) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Single<R> flatMap(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
+    public final <@NonNull R> Single<R> flatMap(@NonNull Function<? super T, ? extends SingleSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMap<>(this, mapper));
     }
@@ -3417,7 +3417,7 @@ public final <R> Single<R> flatMap(@NonNull Function<? super T, ? extends Single
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U, R> Single<R> flatMap(@NonNull Function<? super T, ? extends SingleSource<? extends U>> mapper,
+    public final <@NonNull U, @NonNull R> Single<R> flatMap(@NonNull Function<? super T, ? extends SingleSource<? extends U>> mapper,
             @NonNull BiFunction<? super T, ? super U, ? extends R> combiner) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(combiner, "combiner is null");
@@ -3448,7 +3448,7 @@ public final <U, R> Single<R> flatMap(@NonNull Function<? super T, ? extends Sin
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Single<R> flatMap(
+    public final <@NonNull R> Single<R> flatMap(
             @NonNull Function<? super T, ? extends SingleSource<? extends R>> onSuccessMapper,
             @NonNull Function<? super Throwable, ? extends SingleSource<? extends R>> onErrorMapper) {
         Objects.requireNonNull(onSuccessMapper, "onSuccessMapper is null");
@@ -3476,7 +3476,7 @@ public final <R> Single<R> flatMap(
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Maybe<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
+    public final <@NonNull R> Maybe<R> flatMapMaybe(@NonNull Function<? super T, ? extends MaybeSource<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMapMaybe<>(this, mapper));
     }
@@ -3506,7 +3506,7 @@ public final <R> Maybe<R> flatMapMaybe(@NonNull Function<? super T, ? extends Ma
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Flowable<R> flatMapPublisher(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flatMapPublisher(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMapPublisher<>(this, mapper));
     }
@@ -3537,7 +3537,7 @@ public final <R> Flowable<R> flatMapPublisher(@NonNull Function<? super T, ? ext
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Flowable<U> flattenAsFlowable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Flowable<U> flattenAsFlowable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMapIterableFlowable<>(this, mapper));
     }
@@ -3565,7 +3565,7 @@ public final <U> Flowable<U> flattenAsFlowable(@NonNull Function<? super T, ? ex
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <@NonNull U> Observable<U> flattenAsObservable(@NonNull Function<@NonNull ? super T, @NonNull ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> Observable<U> flattenAsObservable(@NonNull Function<@NonNull ? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlatMapIterableObservable<>(this, mapper));
     }
@@ -3892,7 +3892,7 @@ public final void blockingSubscribe(@NonNull SingleObserver<? super T> observer)
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> Single<R> lift(@NonNull SingleOperator<? extends R, ? super T> lift) {
+    public final <@NonNull R> Single<R> lift(@NonNull SingleOperator<? extends R, ? super T> lift) {
         Objects.requireNonNull(lift, "lift is null");
         return RxJavaPlugins.onAssembly(new SingleLift<>(this, lift));
     }
@@ -4039,7 +4039,7 @@ public final Flowable<T> mergeWith(@NonNull SingleSource<? extends T> other) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> Maybe<U> ofType(@NonNull Class<U> clazz) {
+    public final <@NonNull U> Maybe<U> ofType(@NonNull Class<U> clazz) {
         Objects.requireNonNull(clazz, "clazz is null");
         return filter(Functions.isInstanceOf(clazz)).cast(clazz);
     }
@@ -4333,7 +4333,7 @@ public final Flowable<T> repeat(long times) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Flowable<T> repeatWhen(@NonNull Function<? super Flowable<Object>, ? extends Publisher<@NonNull ?>> handler) {
+    public final Flowable<T> repeatWhen(@NonNull Function<? super Flowable<Object>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         return toFlowable().repeatWhen(handler);
     }
 
@@ -4538,7 +4538,7 @@ public final Single<T> retryUntil(@NonNull BooleanSupplier stop) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final Single<T> retryWhen(@NonNull Function<? super Flowable<Throwable>, ? extends Publisher<@NonNull ?>> handler) {
+    public final Single<T> retryWhen(@NonNull Function<? super Flowable<Throwable>, @NonNull ? extends Publisher<@NonNull ?>> handler) {
         return toSingle(toFlowable().retryWhen(handler));
     }
 
@@ -5211,7 +5211,7 @@ public final Single<T> takeUntil(@NonNull CompletableSource other) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <E> Single<T> takeUntil(@NonNull Publisher<E> other) {
+    public final <@NonNull E> Single<T> takeUntil(@NonNull Publisher<E> other) {
         Objects.requireNonNull(other, "other is null");
         return RxJavaPlugins.onAssembly(new SingleTakeUntil<>(this, other));
     }
@@ -5239,7 +5239,7 @@ public final <E> Single<T> takeUntil(@NonNull Publisher<E> other) {
     @CheckReturnValue
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <E> Single<T> takeUntil(@NonNull SingleSource<? extends E> other) {
+    public final <@NonNull E> Single<T> takeUntil(@NonNull SingleSource<? extends E> other) {
         Objects.requireNonNull(other, "other is null");
         return takeUntil(new SingleToFlowable<E>(other));
     }
@@ -5529,7 +5529,7 @@ public final Single<T> unsubscribeOn(@NonNull Scheduler scheduler) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U, R> Single<R> zipWith(@NonNull SingleSource<U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
+    public final <@NonNull U, @NonNull R> Single<R> zipWith(@NonNull SingleSource<U> other, @NonNull BiFunction<? super T, ? super U, ? extends R> zipper) {
         return zip(this, other, zipper);
     }
 
@@ -5622,7 +5622,7 @@ private static <T> Single<T> toSingle(@NonNull Flowable<T> source) {
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public static <T> Single<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
+    public static <@NonNull T> Single<@NonNull T> fromCompletionStage(@NonNull CompletionStage<T> stage) {
         Objects.requireNonNull(stage, "stage is null");
         return RxJavaPlugins.onAssembly(new SingleFromCompletionStage<>(stage));
     }
@@ -5716,7 +5716,7 @@ public final CompletionStage<T> toCompletionStage() {
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
     @NonNull
-    public final <R> Flowable<R> flattenStreamAsFlowable(@NonNull Function<? super T, ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Flowable<R> flattenStreamAsFlowable(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlattenStreamAsFlowable<>(this, mapper));
     }
@@ -5757,7 +5757,7 @@ public final <R> Flowable<R> flattenStreamAsFlowable(@NonNull Function<? super T
     @CheckReturnValue
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <R> Observable<R> flattenStreamAsObservable(@NonNull Function<? super T, ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> Observable<R> flattenStreamAsObservable(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new SingleFlattenStreamAsObservable<>(this, mapper));
     }
diff --git a/src/main/java/io/reactivex/rxjava3/internal/subscriptions/BasicIntQueueSubscription.java b/src/main/java/io/reactivex/rxjava3/internal/subscriptions/BasicIntQueueSubscription.java
index 1922562340..ab4a6e749b 100644
--- a/src/main/java/io/reactivex/rxjava3/internal/subscriptions/BasicIntQueueSubscription.java
+++ b/src/main/java/io/reactivex/rxjava3/internal/subscriptions/BasicIntQueueSubscription.java
@@ -15,6 +15,7 @@
 
 import java.util.concurrent.atomic.AtomicInteger;
 
+import io.reactivex.rxjava3.annotations.NonNull;
 import io.reactivex.rxjava3.internal.fuseable.QueueSubscription;
 
 /**
@@ -22,7 +23,7 @@
  *
  * @param <T> the value type
  */
-public abstract class BasicIntQueueSubscription<T> extends AtomicInteger implements QueueSubscription<T> {
+public abstract class BasicIntQueueSubscription<@NonNull T> extends AtomicInteger implements QueueSubscription<T> {
 
     private static final long serialVersionUID = -6671519529404341862L;
 
diff --git a/src/main/java/io/reactivex/rxjava3/internal/subscriptions/DeferredScalarSubscription.java b/src/main/java/io/reactivex/rxjava3/internal/subscriptions/DeferredScalarSubscription.java
index e941867b99..544fac8b58 100644
--- a/src/main/java/io/reactivex/rxjava3/internal/subscriptions/DeferredScalarSubscription.java
+++ b/src/main/java/io/reactivex/rxjava3/internal/subscriptions/DeferredScalarSubscription.java
@@ -15,7 +15,7 @@
 
 import org.reactivestreams.Subscriber;
 
-import io.reactivex.rxjava3.annotations.Nullable;
+import io.reactivex.rxjava3.annotations.*;
 
 /**
  * A subscription that signals a single value eventually.
@@ -33,7 +33,7 @@
  * Where exclusively set means any other bits are 0 when that bit is set.
  * @param <T> the value type
  */
-public class DeferredScalarSubscription<T> extends BasicIntQueueSubscription<T> {
+public class DeferredScalarSubscription<@NonNull T> extends BasicIntQueueSubscription<T> {
 
     private static final long serialVersionUID = -2151279923272604993L;
 
diff --git a/src/main/java/io/reactivex/rxjava3/parallel/ParallelFlowable.java b/src/main/java/io/reactivex/rxjava3/parallel/ParallelFlowable.java
index 4a02e8416d..8d5414d27c 100644
--- a/src/main/java/io/reactivex/rxjava3/parallel/ParallelFlowable.java
+++ b/src/main/java/io/reactivex/rxjava3/parallel/ParallelFlowable.java
@@ -59,7 +59,7 @@ public abstract class ParallelFlowable<@NonNull T> {
      */
     @BackpressureSupport(BackpressureKind.SPECIAL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public abstract void subscribe(@NonNull Subscriber<@NonNull ? super T>[] subscribers);
+    public abstract void subscribe(@NonNull Subscriber<? super T>[] subscribers);
 
     /**
      * Returns the number of expected parallel {@link Subscriber}s.
@@ -110,7 +110,7 @@ protected final boolean validate(@NonNull Subscriber<@NonNull ?>[] subscribers)
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <@NonNull T> ParallelFlowable<T> from(@NonNull Publisher<@NonNull ? extends T> source) {
+    public static <@NonNull T> ParallelFlowable<T> from(@NonNull Publisher<? extends T> source) {
         return from(source, Runtime.getRuntime().availableProcessors(), Flowable.bufferSize());
     }
 
@@ -135,7 +135,7 @@ protected final boolean validate(@NonNull Subscriber<@NonNull ?>[] subscribers)
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <@NonNull T> ParallelFlowable<T> from(@NonNull Publisher<@NonNull ? extends T> source, int parallelism) {
+    public static <@NonNull T> ParallelFlowable<T> from(@NonNull Publisher<? extends T> source, int parallelism) {
         return from(source, parallelism, Flowable.bufferSize());
     }
 
@@ -164,7 +164,7 @@ protected final boolean validate(@NonNull Subscriber<@NonNull ?>[] subscribers)
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.FULL)
-    public static <@NonNull T> ParallelFlowable<T> from(@NonNull Publisher<@NonNull ? extends T> source,
+    public static <@NonNull T> ParallelFlowable<T> from(@NonNull Publisher<? extends T> source,
             int parallelism, int prefetch) {
         Objects.requireNonNull(source, "source is null");
         ObjectHelper.verifyPositive(parallelism, "parallelism");
@@ -193,7 +193,7 @@ protected final boolean validate(@NonNull Subscriber<@NonNull ?>[] subscribers)
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends R> mapper) {
+    public final <@NonNull R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends R> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ParallelMap<>(this, mapper));
     }
@@ -223,7 +223,7 @@ public final <R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends R> mapper, @NonNull ParallelFailureHandling errorHandler) {
+    public final <@NonNull R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends R> mapper, @NonNull ParallelFailureHandling errorHandler) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(errorHandler, "errorHandler is null");
         return RxJavaPlugins.onAssembly(new ParallelMapTry<>(this, mapper, errorHandler));
@@ -255,7 +255,7 @@ public final <R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends R> mapper, @NonNull BiFunction<? super Long, ? super Throwable, ParallelFailureHandling> errorHandler) {
+    public final <@NonNull R> ParallelFlowable<R> map(@NonNull Function<? super T, ? extends R> mapper, @NonNull BiFunction<? super Long, ? super Throwable, ParallelFailureHandling> errorHandler) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(errorHandler, "errorHandler is null");
         return RxJavaPlugins.onAssembly(new ParallelMapTry<>(this, mapper, errorHandler));
@@ -473,7 +473,7 @@ public final Flowable<T> reduce(@NonNull BiFunction<T, T, T> reducer) {
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> reduce(@NonNull Supplier<R> initialSupplier, @NonNull BiFunction<R, ? super T, R> reducer) {
+    public final <@NonNull R> ParallelFlowable<R> reduce(@NonNull Supplier<R> initialSupplier, @NonNull BiFunction<R, ? super T, R> reducer) {
         Objects.requireNonNull(initialSupplier, "initialSupplier is null");
         Objects.requireNonNull(reducer, "reducer is null");
         return RxJavaPlugins.onAssembly(new ParallelReduce<>(this, initialSupplier, reducer));
@@ -1044,7 +1044,7 @@ public final ParallelFlowable<T> doOnCancel(@NonNull Action onCancel) {
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <C> ParallelFlowable<C> collect(@NonNull Supplier<? extends C> collectionSupplier, @NonNull BiConsumer<? super C, ? super T> collector) {
+    public final <@NonNull C> ParallelFlowable<C> collect(@NonNull Supplier<? extends C> collectionSupplier, @NonNull BiConsumer<? super C, ? super T> collector) {
         Objects.requireNonNull(collectionSupplier, "collectionSupplier is null");
         Objects.requireNonNull(collector, "collector is null");
         return RxJavaPlugins.onAssembly(new ParallelCollect<>(this, collectionSupplier, collector));
@@ -1126,7 +1126,7 @@ public final <C> ParallelFlowable<C> collect(@NonNull Supplier<? extends C> coll
     @NonNull
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> ParallelFlowable<U> compose(@NonNull ParallelTransformer<T, U> composer) {
+    public final <@NonNull U> ParallelFlowable<U> compose(@NonNull ParallelTransformer<T, U> composer) {
         return RxJavaPlugins.onAssembly(Objects.requireNonNull(composer, "composer is null").apply(this));
     }
 
@@ -1154,7 +1154,7 @@ public final <U> ParallelFlowable<U> compose(@NonNull ParallelTransformer<T, U>
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> flatMap(@NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> ParallelFlowable<R> flatMap(@NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return flatMap(mapper, false, Flowable.bufferSize(), Flowable.bufferSize());
     }
 
@@ -1184,8 +1184,8 @@ public final <R> ParallelFlowable<R> flatMap(@NonNull Function<? super T, ? exte
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> flatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, boolean delayError) {
+    public final <@NonNull R> ParallelFlowable<R> flatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, boolean delayError) {
         return flatMap(mapper, delayError, Flowable.bufferSize(), Flowable.bufferSize());
     }
 
@@ -1218,8 +1218,8 @@ public final <R> ParallelFlowable<R> flatMap(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> flatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper, boolean delayError, int maxConcurrency) {
+    public final <@NonNull R> ParallelFlowable<R> flatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper, boolean delayError, int maxConcurrency) {
         return flatMap(mapper, delayError, maxConcurrency, Flowable.bufferSize());
     }
 
@@ -1252,8 +1252,8 @@ public final <R> ParallelFlowable<R> flatMap(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> flatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> ParallelFlowable<R> flatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             boolean delayError, int maxConcurrency, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(maxConcurrency, "maxConcurrency");
@@ -1284,8 +1284,8 @@ public final <R> ParallelFlowable<R> flatMap(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> concatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> ParallelFlowable<R> concatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper) {
         return concatMap(mapper, 2);
     }
 
@@ -1315,8 +1315,8 @@ public final <R> ParallelFlowable<R> concatMap(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> concatMap(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> ParallelFlowable<R> concatMap(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
             int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -1348,8 +1348,8 @@ public final <R> ParallelFlowable<R> concatMap(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> concatMapDelayError(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> ParallelFlowable<R> concatMapDelayError(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
                     boolean tillTheEnd) {
         return concatMapDelayError(mapper, 2, tillTheEnd);
     }
@@ -1381,8 +1381,8 @@ public final <R> ParallelFlowable<R> concatMapDelayError(
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <R> ParallelFlowable<R> concatMapDelayError(
-            @NonNull Function<? super T, ? extends Publisher<@NonNull ? extends R>> mapper,
+    public final <@NonNull R> ParallelFlowable<R> concatMapDelayError(
+            @NonNull Function<? super T, @NonNull ? extends Publisher<? extends R>> mapper,
                     int prefetch, boolean tillTheEnd) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
@@ -1419,7 +1419,7 @@ public final <R> ParallelFlowable<R> concatMapDelayError(
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <U> ParallelFlowable<U> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper) {
+    public final <@NonNull U> ParallelFlowable<U> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper) {
         return flatMapIterable(mapper, Flowable.bufferSize());
     }
 
@@ -1455,7 +1455,7 @@ public final <U> ParallelFlowable<U> flatMapIterable(@NonNull Function<? super T
     @NonNull
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <U> ParallelFlowable<U> flatMapIterable(@NonNull Function<? super T, ? extends Iterable<@NonNull ? extends U>> mapper, int bufferSize) {
+    public final <@NonNull U> ParallelFlowable<U> flatMapIterable(@NonNull Function<? super T, @NonNull ? extends Iterable<? extends U>> mapper, int bufferSize) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(bufferSize, "bufferSize");
         return RxJavaPlugins.onAssembly(new ParallelFlatMapIterable<>(this, mapper, bufferSize));
@@ -1486,7 +1486,7 @@ public final <U> ParallelFlowable<U> flatMapIterable(@NonNull Function<? super T
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Optional<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, @NonNull Optional<? extends R>> mapper) {
         Objects.requireNonNull(mapper, "mapper is null");
         return RxJavaPlugins.onAssembly(new ParallelMapOptional<>(this, mapper));
     }
@@ -1516,7 +1516,7 @@ public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Op
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Optional<@NonNull ? extends R>> mapper, @NonNull ParallelFailureHandling errorHandler) {
+    public final <@NonNull R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, @NonNull Optional<? extends R>> mapper, @NonNull ParallelFailureHandling errorHandler) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(errorHandler, "errorHandler is null");
         return RxJavaPlugins.onAssembly(new ParallelMapTryOptional<>(this, mapper, errorHandler));
@@ -1548,7 +1548,7 @@ public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Op
     @NonNull
     @SchedulerSupport(SchedulerSupport.NONE)
     @BackpressureSupport(BackpressureKind.PASS_THROUGH)
-    public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Optional<@NonNull ? extends R>> mapper, @NonNull BiFunction<? super Long, ? super Throwable, ParallelFailureHandling> errorHandler) {
+    public final <@NonNull R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, @NonNull Optional<? extends R>> mapper, @NonNull BiFunction<? super Long, ? super Throwable, ParallelFailureHandling> errorHandler) {
         Objects.requireNonNull(mapper, "mapper is null");
         Objects.requireNonNull(errorHandler, "errorHandler is null");
         return RxJavaPlugins.onAssembly(new ParallelMapTryOptional<>(this, mapper, errorHandler));
@@ -1604,7 +1604,7 @@ public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Op
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> ParallelFlowable<R> flatMapStream(@NonNull Function<? super T, ? extends Stream<@NonNull ? extends R>> mapper) {
+    public final <@NonNull R> ParallelFlowable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper) {
         return flatMapStream(mapper, Flowable.bufferSize());
     }
 
@@ -1658,7 +1658,7 @@ public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Op
     @BackpressureSupport(BackpressureKind.FULL)
     @SchedulerSupport(SchedulerSupport.NONE)
     @NonNull
-    public final <@NonNull R> ParallelFlowable<R> flatMapStream(@NonNull Function<? super T, ? extends Stream<@NonNull ? extends R>> mapper, int prefetch) {
+    public final <@NonNull R> ParallelFlowable<R> flatMapStream(@NonNull Function<? super T, @NonNull ? extends Stream<? extends R>> mapper, int prefetch) {
         Objects.requireNonNull(mapper, "mapper is null");
         ObjectHelper.verifyPositive(prefetch, "prefetch");
         return RxJavaPlugins.onAssembly(new ParallelFlatMapStream<>(this, mapper, prefetch));
@@ -1688,7 +1688,7 @@ public final <R> ParallelFlowable<R> mapOptional(@NonNull Function<? super T, Op
     @NonNull
     @BackpressureSupport(BackpressureKind.UNBOUNDED_IN)
     @SchedulerSupport(SchedulerSupport.NONE)
-    public final <A, @NonNull R> Flowable<R> collect(@NonNull Collector<T, A, R> collector) {
+    public final <@NonNull A, @NonNull R> Flowable<R> collect(@NonNull Collector<T, A, R> collector) {
         Objects.requireNonNull(collector, "collector is null");
         return RxJavaPlugins.onAssembly(new ParallelCollector<>(this, collector));
     }
diff --git a/src/main/java/io/reactivex/rxjava3/plugins/RxJavaPlugins.java b/src/main/java/io/reactivex/rxjava3/plugins/RxJavaPlugins.java
index 58cb730bf6..506fb65c67 100644
--- a/src/main/java/io/reactivex/rxjava3/plugins/RxJavaPlugins.java
+++ b/src/main/java/io/reactivex/rxjava3/plugins/RxJavaPlugins.java
@@ -96,26 +96,26 @@ public final class RxJavaPlugins {
 
     @SuppressWarnings("rawtypes")
     @Nullable
-    static volatile BiFunction<? super Flowable, ? super Subscriber, ? extends Subscriber> onFlowableSubscribe;
+    static volatile BiFunction<? super Flowable, @NonNull ? super Subscriber, @NonNull ? extends Subscriber> onFlowableSubscribe;
 
     @SuppressWarnings("rawtypes")
     @Nullable
-    static volatile BiFunction<? super Maybe, ? super MaybeObserver, ? extends MaybeObserver> onMaybeSubscribe;
+    static volatile BiFunction<? super Maybe, @NonNull ? super MaybeObserver, @NonNull ? extends MaybeObserver> onMaybeSubscribe;
 
     @SuppressWarnings("rawtypes")
     @Nullable
-    static volatile BiFunction<? super Observable, ? super Observer, ? extends Observer> onObservableSubscribe;
+    static volatile BiFunction<? super Observable, @NonNull ? super Observer, @NonNull ? extends Observer> onObservableSubscribe;
 
     @SuppressWarnings("rawtypes")
     @Nullable
-    static volatile BiFunction<? super Single, ? super SingleObserver, ? extends SingleObserver> onSingleSubscribe;
+    static volatile BiFunction<? super Single, @NonNull ? super SingleObserver, @NonNull ? extends SingleObserver> onSingleSubscribe;
 
     @Nullable
-    static volatile BiFunction<? super Completable, ? super CompletableObserver, ? extends CompletableObserver> onCompletableSubscribe;
+    static volatile BiFunction<? super Completable, @NonNull ? super CompletableObserver, @NonNull ? extends CompletableObserver> onCompletableSubscribe;
 
     @SuppressWarnings("rawtypes")
     @Nullable
-    static volatile BiFunction<? super ParallelFlowable, ? super Subscriber[], ? extends Subscriber[]> onParallelSubscribe;
+    static volatile BiFunction<? super ParallelFlowable, @NonNull ? super Subscriber[], @NonNull ? extends Subscriber[]> onParallelSubscribe;
 
     @Nullable
     static volatile BooleanSupplier onBeforeBlocking;
@@ -667,7 +667,7 @@ public static void setSingleSchedulerHandler(@Nullable Function<? super Schedule
      * @return the hook function, may be null
      */
     @Nullable
-    public static BiFunction<? super Completable, ? super CompletableObserver, ? extends CompletableObserver> getOnCompletableSubscribe() {
+    public static BiFunction<? super Completable, @NonNull ? super CompletableObserver, @NonNull ? extends CompletableObserver> getOnCompletableSubscribe() {
         return onCompletableSubscribe;
     }
 
@@ -697,7 +697,7 @@ public static void setSingleSchedulerHandler(@Nullable Function<? super Schedule
      */
     @Nullable
     @SuppressWarnings("rawtypes")
-    public static BiFunction<? super Flowable, ? super Subscriber, ? extends Subscriber> getOnFlowableSubscribe() {
+    public static BiFunction<? super Flowable, @NonNull ? super Subscriber, @NonNull ? extends Subscriber> getOnFlowableSubscribe() {
         return onFlowableSubscribe;
     }
 
@@ -707,7 +707,7 @@ public static void setSingleSchedulerHandler(@Nullable Function<? super Schedule
      */
     @Nullable
     @SuppressWarnings("rawtypes")
-    public static BiFunction<? super Maybe, ? super MaybeObserver, ? extends MaybeObserver> getOnMaybeSubscribe() {
+    public static BiFunction<? super Maybe, @NonNull ? super MaybeObserver, @NonNull ? extends MaybeObserver> getOnMaybeSubscribe() {
         return onMaybeSubscribe;
     }
 
@@ -737,7 +737,7 @@ public static void setSingleSchedulerHandler(@Nullable Function<? super Schedule
      */
     @Nullable
     @SuppressWarnings("rawtypes")
-    public static BiFunction<? super Single, ? super SingleObserver, ? extends SingleObserver> getOnSingleSubscribe() {
+    public static BiFunction<? super Single, @NonNull ? super SingleObserver, @NonNull ? extends SingleObserver> getOnSingleSubscribe() {
         return onSingleSubscribe;
     }
 
@@ -767,7 +767,7 @@ public static void setSingleSchedulerHandler(@Nullable Function<? super Schedule
      */
     @Nullable
     @SuppressWarnings("rawtypes")
-    public static BiFunction<? super Observable, ? super Observer, ? extends Observer> getOnObservableSubscribe() {
+    public static BiFunction<? super Observable, @NonNull ? super Observer, @NonNull ? extends Observer> getOnObservableSubscribe() {
         return onObservableSubscribe;
     }
 
@@ -787,7 +787,7 @@ public static void setOnCompletableAssembly(@Nullable Function<? super Completab
      * @param onCompletableSubscribe the hook function to set, null allowed
      */
     public static void setOnCompletableSubscribe(
-            @Nullable BiFunction<? super Completable, ? super CompletableObserver, ? extends CompletableObserver> onCompletableSubscribe) {
+            @Nullable BiFunction<? super Completable, @NonNull ? super CompletableObserver, @NonNull ? extends CompletableObserver> onCompletableSubscribe) {
         if (lockdown) {
             throw new IllegalStateException("Plugins can't be changed anymore");
         }
@@ -835,7 +835,7 @@ public static void setOnConnectableFlowableAssembly(@Nullable Function<? super C
      * @param onFlowableSubscribe the hook function to set, null allowed
      */
     @SuppressWarnings("rawtypes")
-    public static void setOnFlowableSubscribe(@Nullable BiFunction<? super Flowable, ? super Subscriber, ? extends Subscriber> onFlowableSubscribe) {
+    public static void setOnFlowableSubscribe(@Nullable BiFunction<? super Flowable, @NonNull ? super Subscriber, @NonNull ? extends Subscriber> onFlowableSubscribe) {
         if (lockdown) {
             throw new IllegalStateException("Plugins can't be changed anymore");
         }
@@ -847,7 +847,7 @@ public static void setOnFlowableSubscribe(@Nullable BiFunction<? super Flowable,
      * @param onMaybeSubscribe the hook function to set, null allowed
      */
     @SuppressWarnings("rawtypes")
-    public static void setOnMaybeSubscribe(@Nullable BiFunction<? super Maybe, MaybeObserver, ? extends MaybeObserver> onMaybeSubscribe) {
+    public static void setOnMaybeSubscribe(@Nullable BiFunction<? super Maybe, @NonNull MaybeObserver, @NonNull ? extends MaybeObserver> onMaybeSubscribe) {
         if (lockdown) {
             throw new IllegalStateException("Plugins can't be changed anymore");
         }
@@ -884,7 +884,7 @@ public static void setOnConnectableObservableAssembly(@Nullable Function<? super
      */
     @SuppressWarnings("rawtypes")
     public static void setOnObservableSubscribe(
-            @Nullable BiFunction<? super Observable, ? super Observer, ? extends Observer> onObservableSubscribe) {
+            @Nullable BiFunction<? super Observable, @NonNull ? super Observer, @NonNull ? extends Observer> onObservableSubscribe) {
         if (lockdown) {
             throw new IllegalStateException("Plugins can't be changed anymore");
         }
@@ -908,7 +908,7 @@ public static void setOnSingleAssembly(@Nullable Function<? super Single, ? exte
      * @param onSingleSubscribe the hook function to set, null allowed
      */
     @SuppressWarnings("rawtypes")
-    public static void setOnSingleSubscribe(@Nullable BiFunction<? super Single, ? super SingleObserver, ? extends SingleObserver> onSingleSubscribe) {
+    public static void setOnSingleSubscribe(@Nullable BiFunction<? super Single, @NonNull ? super SingleObserver, @NonNull ? extends SingleObserver> onSingleSubscribe) {
         if (lockdown) {
             throw new IllegalStateException("Plugins can't be changed anymore");
         }
@@ -924,8 +924,8 @@ public static void setOnSingleSubscribe(@Nullable BiFunction<? super Single, ? s
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> Subscriber<@NonNull ? super T> onSubscribe(@NonNull Flowable<T> source, @NonNull Subscriber<@NonNull ? super T> subscriber) {
-        BiFunction<? super Flowable, ? super Subscriber, ? extends Subscriber> f = onFlowableSubscribe;
+    public static <@NonNull T> Subscriber<? super T> onSubscribe(@NonNull Flowable<T> source, @NonNull Subscriber<? super T> subscriber) {
+        BiFunction<? super Flowable, @NonNull ? super Subscriber, @NonNull ? extends Subscriber> f = onFlowableSubscribe;
         if (f != null) {
             return apply(f, source, subscriber);
         }
@@ -941,8 +941,8 @@ public static void setOnSingleSubscribe(@Nullable BiFunction<? super Single, ? s
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> Observer<? super T> onSubscribe(@NonNull Observable<T> source, @NonNull Observer<? super T> observer) {
-        BiFunction<? super Observable, ? super Observer, ? extends Observer> f = onObservableSubscribe;
+    public static <@NonNull T> Observer<? super T> onSubscribe(@NonNull Observable<T> source, @NonNull Observer<? super T> observer) {
+        BiFunction<? super Observable, @NonNull ? super Observer, @NonNull ? extends Observer> f = onObservableSubscribe;
         if (f != null) {
             return apply(f, source, observer);
         }
@@ -958,8 +958,8 @@ public static <T> Observer<? super T> onSubscribe(@NonNull Observable<T> source,
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> SingleObserver<? super T> onSubscribe(@NonNull Single<T> source, @NonNull SingleObserver<? super T> observer) {
-        BiFunction<? super Single, ? super SingleObserver, ? extends SingleObserver> f = onSingleSubscribe;
+    public static <@NonNull T> SingleObserver<? super T> onSubscribe(@NonNull Single<T> source, @NonNull SingleObserver<? super T> observer) {
+        BiFunction<? super Single, @NonNull ? super SingleObserver, @NonNull ? extends SingleObserver> f = onSingleSubscribe;
         if (f != null) {
             return apply(f, source, observer);
         }
@@ -974,7 +974,7 @@ public static <T> SingleObserver<? super T> onSubscribe(@NonNull Single<T> sourc
      */
     @NonNull
     public static CompletableObserver onSubscribe(@NonNull Completable source, @NonNull CompletableObserver observer) {
-        BiFunction<? super Completable, ? super CompletableObserver, ? extends CompletableObserver> f = onCompletableSubscribe;
+        BiFunction<? super Completable, @NonNull ? super CompletableObserver, @NonNull ? extends CompletableObserver> f = onCompletableSubscribe;
         if (f != null) {
             return apply(f, source, observer);
         }
@@ -990,8 +990,8 @@ public static CompletableObserver onSubscribe(@NonNull Completable source, @NonN
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> MaybeObserver<? super T> onSubscribe(@NonNull Maybe<T> source, @NonNull MaybeObserver<? super T> observer) {
-        BiFunction<? super Maybe, ? super MaybeObserver, ? extends MaybeObserver> f = onMaybeSubscribe;
+    public static <@NonNull T> MaybeObserver<? super T> onSubscribe(@NonNull Maybe<T> source, @NonNull MaybeObserver<? super T> observer) {
+        BiFunction<? super Maybe, @NonNull ? super MaybeObserver, @NonNull ? extends MaybeObserver> f = onMaybeSubscribe;
         if (f != null) {
             return apply(f, source, observer);
         }
@@ -1007,8 +1007,8 @@ public static <T> MaybeObserver<? super T> onSubscribe(@NonNull Maybe<T> source,
      */
     @SuppressWarnings({ "rawtypes" })
     @NonNull
-    public static <T> Subscriber<@NonNull ? super T>[] onSubscribe(@NonNull ParallelFlowable<T> source, @NonNull Subscriber<@NonNull ? super T>[] subscribers) {
-        BiFunction<? super ParallelFlowable, ? super Subscriber[], ? extends Subscriber[]> f = onParallelSubscribe;
+    public static <@NonNull T> Subscriber<? super T>[] onSubscribe(@NonNull ParallelFlowable<T> source, @NonNull Subscriber<? super T>[] subscribers) {
+        BiFunction<? super ParallelFlowable, @NonNull ? super Subscriber[], @NonNull ? extends Subscriber[]> f = onParallelSubscribe;
         if (f != null) {
             return apply(f, source, subscribers);
         }
@@ -1023,7 +1023,7 @@ public static <T> MaybeObserver<? super T> onSubscribe(@NonNull Maybe<T> source,
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> Maybe<T> onAssembly(@NonNull Maybe<T> source) {
+    public static <@NonNull T> Maybe<T> onAssembly(@NonNull Maybe<T> source) {
         Function<? super Maybe, ? extends Maybe> f = onMaybeAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1039,7 +1039,7 @@ public static <T> Maybe<T> onAssembly(@NonNull Maybe<T> source) {
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> Flowable<T> onAssembly(@NonNull Flowable<T> source) {
+    public static <@NonNull T> Flowable<T> onAssembly(@NonNull Flowable<T> source) {
         Function<? super Flowable, ? extends Flowable> f = onFlowableAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1055,7 +1055,7 @@ public static <T> Flowable<T> onAssembly(@NonNull Flowable<T> source) {
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> ConnectableFlowable<T> onAssembly(@NonNull ConnectableFlowable<T> source) {
+    public static <@NonNull T> ConnectableFlowable<T> onAssembly(@NonNull ConnectableFlowable<T> source) {
         Function<? super ConnectableFlowable, ? extends ConnectableFlowable> f = onConnectableFlowableAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1071,7 +1071,7 @@ public static <T> ConnectableFlowable<T> onAssembly(@NonNull ConnectableFlowable
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> Observable<T> onAssembly(@NonNull Observable<T> source) {
+    public static <@NonNull T> Observable<T> onAssembly(@NonNull Observable<T> source) {
         Function<? super Observable, ? extends Observable> f = onObservableAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1087,7 +1087,7 @@ public static <T> Observable<T> onAssembly(@NonNull Observable<T> source) {
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> ConnectableObservable<T> onAssembly(@NonNull ConnectableObservable<T> source) {
+    public static <@NonNull T> ConnectableObservable<T> onAssembly(@NonNull ConnectableObservable<T> source) {
         Function<? super ConnectableObservable, ? extends ConnectableObservable> f = onConnectableObservableAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1103,7 +1103,7 @@ public static <T> ConnectableObservable<T> onAssembly(@NonNull ConnectableObserv
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> Single<T> onAssembly(@NonNull Single<T> source) {
+    public static <@NonNull T> Single<T> onAssembly(@NonNull Single<T> source) {
         Function<? super Single, ? extends Single> f = onSingleAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1158,7 +1158,7 @@ public static void setOnParallelAssembly(@Nullable Function<? super ParallelFlow
      * @since 3.1.0
      */
     @SuppressWarnings("rawtypes")
-    public static void setOnParallelSubscribe(@Nullable BiFunction<? super ParallelFlowable, ? super Subscriber[], ? extends Subscriber[]> handler) {
+    public static void setOnParallelSubscribe(@Nullable BiFunction<? super ParallelFlowable, @NonNull ? super Subscriber[], @NonNull ? extends Subscriber[]> handler) {
         if (lockdown) {
             throw new IllegalStateException("Plugins can't be changed anymore");
         }
@@ -1173,7 +1173,7 @@ public static void setOnParallelSubscribe(@Nullable BiFunction<? super ParallelF
      */
     @SuppressWarnings("rawtypes")
     @Nullable
-    public static BiFunction<? super ParallelFlowable, ? super Subscriber[], ? extends Subscriber[]> getOnParallelSubscribe() {
+    public static BiFunction<? super ParallelFlowable, @NonNull ? super Subscriber[], @NonNull ? extends Subscriber[]> getOnParallelSubscribe() {
         return onParallelSubscribe;
     }
 
@@ -1187,7 +1187,7 @@ public static void setOnParallelSubscribe(@Nullable BiFunction<? super ParallelF
      */
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @NonNull
-    public static <T> ParallelFlowable<T> onAssembly(@NonNull ParallelFlowable<T> source) {
+    public static <@NonNull T> ParallelFlowable<T> onAssembly(@NonNull ParallelFlowable<T> source) {
         Function<? super ParallelFlowable, ? extends ParallelFlowable> f = onParallelAssembly;
         if (f != null) {
             return apply(f, source);
@@ -1312,7 +1312,7 @@ public static Scheduler createSingleScheduler(@NonNull ThreadFactory threadFacto
      * @return the result of the function call
      */
     @NonNull
-    static <T, R> R apply(@NonNull Function<T, R> f, @NonNull T t) {
+    static <@NonNull T, @NonNull R> R apply(@NonNull Function<T, R> f, @NonNull T t) {
         try {
             return f.apply(t);
         } catch (Throwable ex) {
@@ -1332,7 +1332,7 @@ static <T, R> R apply(@NonNull Function<T, R> f, @NonNull T t) {
      * @return the result of the function call
      */
     @NonNull
-    static <T, U, R> R apply(@NonNull BiFunction<T, U, R> f, @NonNull T t, @NonNull U u) {
+    static <@NonNull T, @NonNull U, @NonNull R> R apply(@NonNull BiFunction<T, U, R> f, @NonNull T t, @NonNull U u) {
         try {
             return f.apply(t, u);
         } catch (Throwable ex) {
diff --git a/src/main/java/io/reactivex/rxjava3/processors/AsyncProcessor.java b/src/main/java/io/reactivex/rxjava3/processors/AsyncProcessor.java
index 12a96ad5ae..b20c8b23ae 100644
--- a/src/main/java/io/reactivex/rxjava3/processors/AsyncProcessor.java
+++ b/src/main/java/io/reactivex/rxjava3/processors/AsyncProcessor.java
@@ -114,7 +114,7 @@
  * </code></pre>
  * @param <T> the value type
  */
-public final class AsyncProcessor<T> extends FlowableProcessor<T> {
+public final class AsyncProcessor<@NonNull T> extends FlowableProcessor<T> {
 
     @SuppressWarnings("rawtypes")
     static final AsyncSubscription[] EMPTY = new AsyncSubscription[0];
@@ -229,7 +229,7 @@ public Throwable getThrowable() {
     }
 
     @Override
-    protected void subscribeActual(@NonNull Subscriber<@NonNull ? super T> s) {
+    protected void subscribeActual(@NonNull Subscriber<? super T> s) {
         AsyncSubscription<T> as = new AsyncSubscription<>(s, this);
         s.onSubscribe(as);
         if (add(as)) {
@@ -337,12 +337,12 @@ public T getValue() {
         return subscribers.get() == TERMINATED ? value : null;
     }
 
-    static final class AsyncSubscription<T> extends DeferredScalarSubscription<T> {
+    static final class AsyncSubscription<@NonNull T> extends DeferredScalarSubscription<T> {
         private static final long serialVersionUID = 5629876084736248016L;
 
         final AsyncProcessor<T> parent;
 
-        AsyncSubscription(Subscriber<@NonNull ? super T> actual, AsyncProcessor<T> parent) {
+        AsyncSubscription(Subscriber<? super T> actual, AsyncProcessor<T> parent) {
             super(actual);
             this.parent = parent;
         }
diff --git a/src/main/java/io/reactivex/rxjava3/processors/BehaviorProcessor.java b/src/main/java/io/reactivex/rxjava3/processors/BehaviorProcessor.java
index 681d605228..56c9d881f0 100644
--- a/src/main/java/io/reactivex/rxjava3/processors/BehaviorProcessor.java
+++ b/src/main/java/io/reactivex/rxjava3/processors/BehaviorProcessor.java
@@ -160,7 +160,7 @@
  * @param <T>
  *          the type of item expected to be observed and emitted by the Processor
  */
-public final class BehaviorProcessor<T> extends FlowableProcessor<T> {
+public final class BehaviorProcessor<@NonNull T> extends FlowableProcessor<T> {
     final AtomicReference<BehaviorSubscription<T>[]> subscribers;
 
     static final Object[] EMPTY_ARRAY = new Object[0];
@@ -239,7 +239,7 @@ public static <T> BehaviorProcessor<T> create() {
     }
 
     @Override
-    protected void subscribeActual(@NonNull Subscriber<@NonNull ? super T> s) {
+    protected void subscribeActual(@NonNull Subscriber<? super T> s) {
         BehaviorSubscription<T> bs = new BehaviorSubscription<>(s, this);
         s.onSubscribe(bs);
         if (add(bs)) {
@@ -472,7 +472,7 @@ static final class BehaviorSubscription<@NonNull T> extends AtomicLong implement
 
         private static final long serialVersionUID = 3293175281126227086L;
 
-        final Subscriber<@NonNull ? super T> downstream;
+        final Subscriber<? super T> downstream;
         final BehaviorProcessor<T> state;
 
         boolean next;
@@ -485,7 +485,7 @@ static final class BehaviorSubscription<@NonNull T> extends AtomicLong implement
 
         long index;
 
-        BehaviorSubscription(Subscriber<@NonNull ? super T> actual, BehaviorProcessor<T> state) {
+        BehaviorSubscription(Subscriber<? super T> actual, BehaviorProcessor<T> state) {
             this.downstream = actual;
             this.state = state;
         }
diff --git a/src/main/java/io/reactivex/rxjava3/processors/MulticastProcessor.java b/src/main/java/io/reactivex/rxjava3/processors/MulticastProcessor.java
index 55e19f7d1e..a3200346d3 100644
--- a/src/main/java/io/reactivex/rxjava3/processors/MulticastProcessor.java
+++ b/src/main/java/io/reactivex/rxjava3/processors/MulticastProcessor.java
@@ -130,7 +130,7 @@
  */
 @BackpressureSupport(BackpressureKind.FULL)
 @SchedulerSupport(SchedulerSupport.NONE)
-public final class MulticastProcessor<T> extends FlowableProcessor<T> {
+public final class MulticastProcessor<@NonNull T> extends FlowableProcessor<T> {
 
     final AtomicInteger wip;
 
@@ -370,7 +370,7 @@ public Throwable getThrowable() {
     }
 
     @Override
-    protected void subscribeActual(@NonNull Subscriber<@NonNull ? super T> s) {
+    protected void subscribeActual(@NonNull Subscriber<? super T> s) {
         MulticastSubscription<T> ms = new MulticastSubscription<>(s, this);
         s.onSubscribe(ms);
         if (add(ms)) {
@@ -584,17 +584,17 @@ void drain() {
         }
     }
 
-    static final class MulticastSubscription<T> extends AtomicLong implements Subscription {
+    static final class MulticastSubscription<@NonNull T> extends AtomicLong implements Subscription {
 
         private static final long serialVersionUID = -363282618957264509L;
 
-        final Subscriber<@NonNull ? super T> downstream;
+        final Subscriber<? super T> downstream;
 
         final MulticastProcessor<T> parent;
 
         long emitted;
 
-        MulticastSubscription(Subscriber<@NonNull ? super T> actual, MulticastProcessor<T> parent) {
+        MulticastSubscription(Subscriber<? super T> actual, MulticastProcessor<T> parent) {
             this.downstream = actual;
             this.parent = parent;
         }
diff --git a/src/main/java/io/reactivex/rxjava3/processors/PublishProcessor.java b/src/main/java/io/reactivex/rxjava3/processors/PublishProcessor.java
index c02a0e937e..79f38a06ec 100644
--- a/src/main/java/io/reactivex/rxjava3/processors/PublishProcessor.java
+++ b/src/main/java/io/reactivex/rxjava3/processors/PublishProcessor.java
@@ -107,7 +107,7 @@
  * @param <T> the value type multicasted to Subscribers.
  * @see MulticastProcessor
  */
-public final class PublishProcessor<T> extends FlowableProcessor<T> {
+public final class PublishProcessor<@NonNull T> extends FlowableProcessor<T> {
     /** The terminated indicator for the subscribers array. */
     @SuppressWarnings("rawtypes")
     static final PublishSubscription[] TERMINATED = new PublishSubscription[0];
@@ -142,7 +142,7 @@ public static <T> PublishProcessor<T> create() {
     }
 
     @Override
-    protected void subscribeActual(@NonNull Subscriber<@NonNull ? super T> t) {
+    protected void subscribeActual(@NonNull Subscriber<? super T> t) {
         PublishSubscription<T> ps = new PublishSubscription<>(t, this);
         t.onSubscribe(ps);
         if (add(ps)) {
@@ -341,7 +341,7 @@ static final class PublishSubscription<@NonNull T> extends AtomicLong implements
 
         private static final long serialVersionUID = 3562861878281475070L;
         /** The actual subscriber. */
-        final Subscriber<@NonNull ? super T> downstream;
+        final Subscriber<? super T> downstream;
         /** The parent processor servicing this subscriber. */
         final PublishProcessor<T> parent;
 
@@ -350,7 +350,7 @@ static final class PublishSubscription<@NonNull T> extends AtomicLong implements
          * @param actual the actual subscriber
          * @param parent the parent PublishProcessor
          */
-        PublishSubscription(Subscriber<@NonNull ? super T> actual, PublishProcessor<T> parent) {
+        PublishSubscription(Subscriber<? super T> actual, PublishProcessor<T> parent) {
             this.downstream = actual;
             this.parent = parent;
         }
diff --git a/src/main/java/io/reactivex/rxjava3/processors/ReplayProcessor.java b/src/main/java/io/reactivex/rxjava3/processors/ReplayProcessor.java
index 1a0fdfebfb..ae6a7d3960 100644
--- a/src/main/java/io/reactivex/rxjava3/processors/ReplayProcessor.java
+++ b/src/main/java/io/reactivex/rxjava3/processors/ReplayProcessor.java
@@ -141,7 +141,7 @@
  *
  * @param <T> the value type
  */
-public final class ReplayProcessor<T> extends FlowableProcessor<T> {
+public final class ReplayProcessor<@NonNull T> extends FlowableProcessor<T> {
     /** An empty array to avoid allocation in getValues(). */
     private static final Object[] EMPTY_ARRAY = new Object[0];
 
@@ -345,7 +345,7 @@ public static <T> ReplayProcessor<T> createWithTimeAndSize(long maxAge, @NonNull
     }
 
     @Override
-    protected void subscribeActual(Subscriber<@NonNull ? super T> s) {
+    protected void subscribeActual(Subscriber<? super T> s) {
         ReplaySubscription<T> rs = new ReplaySubscription<>(s, this);
         s.onSubscribe(rs);
 
@@ -584,7 +584,7 @@ void remove(ReplaySubscription<T> rs) {
      *
      * @param <T> the value type
      */
-    interface ReplayBuffer<T> {
+    interface ReplayBuffer<@NonNull T> {
 
         void next(T value);
 
@@ -612,10 +612,10 @@ interface ReplayBuffer<T> {
         void trimHead();
     }
 
-    static final class ReplaySubscription<T> extends AtomicInteger implements Subscription {
+    static final class ReplaySubscription<@NonNull T> extends AtomicInteger implements Subscription {
 
         private static final long serialVersionUID = 466549804534799122L;
-        final Subscriber<@NonNull ? super T> downstream;
+        final Subscriber<? super T> downstream;
         final ReplayProcessor<T> state;
 
         Object index;
@@ -626,7 +626,7 @@ static final class ReplaySubscription<T> extends AtomicInteger implements Subscr
 
         long emitted;
 
-        ReplaySubscription(Subscriber<@NonNull ? super T> actual, ReplayProcessor<T> state) {
+        ReplaySubscription(Subscriber<? super T> actual, ReplayProcessor<T> state) {
             this.downstream = actual;
             this.state = state;
             this.requested = new AtomicLong();
@@ -728,7 +728,7 @@ public void replay(ReplaySubscription<T> rs) {
 
             int missed = 1;
             final List<T> b = buffer;
-            final Subscriber<@NonNull ? super T> a = rs.downstream;
+            final Subscriber<? super T> a = rs.downstream;
 
             Integer indexObject = (Integer)rs.index;
             int index;
@@ -846,7 +846,7 @@ static final class TimedNode<T> extends AtomicReference<TimedNode<T>> {
         }
     }
 
-    static final class SizeBoundReplayBuffer<T>
+    static final class SizeBoundReplayBuffer<@NonNull T>
     implements ReplayBuffer<T> {
 
         final int maxSize;
@@ -967,7 +967,7 @@ public void replay(ReplaySubscription<T> rs) {
             }
 
             int missed = 1;
-            final Subscriber<@NonNull ? super T> a = rs.downstream;
+            final Subscriber<? super T> a = rs.downstream;
 
             Node<T> index = (Node<T>)rs.index;
             if (index == null) {
@@ -1253,7 +1253,7 @@ public void replay(ReplaySubscription<T> rs) {
             }
 
             int missed = 1;
-            final Subscriber<@NonNull ? super T> a = rs.downstream;
+            final Subscriber<? super T> a = rs.downstream;
 
             TimedNode<T> index = (TimedNode<T>)rs.index;
             if (index == null) {
diff --git a/src/main/java/io/reactivex/rxjava3/processors/UnicastProcessor.java b/src/main/java/io/reactivex/rxjava3/processors/UnicastProcessor.java
index 6ba938e9e4..60cc033bd6 100644
--- a/src/main/java/io/reactivex/rxjava3/processors/UnicastProcessor.java
+++ b/src/main/java/io/reactivex/rxjava3/processors/UnicastProcessor.java
@@ -147,7 +147,7 @@
  * @param <T> the value type received and emitted by this Processor subclass
  * @since 2.0
  */
-public final class UnicastProcessor<T> extends FlowableProcessor<T> {
+public final class UnicastProcessor<@NonNull T> extends FlowableProcessor<T> {
 
     final SpscLinkedArrayQueue<T> queue;
 
@@ -159,7 +159,7 @@ public final class UnicastProcessor<T> extends FlowableProcessor<T> {
 
     Throwable error;
 
-    final AtomicReference<Subscriber<@NonNull ? super T>> downstream;
+    final AtomicReference<Subscriber<? super T>> downstream;
 
     volatile boolean cancelled;
 
@@ -282,7 +282,7 @@ void doTerminate() {
         }
     }
 
-    void drainRegular(Subscriber<@NonNull ? super T> a) {
+    void drainRegular(Subscriber<? super T> a) {
         int missed = 1;
 
         final SpscLinkedArrayQueue<T> q = queue;
@@ -326,7 +326,7 @@ void drainRegular(Subscriber<@NonNull ? super T> a) {
         }
     }
 
-    void drainFused(Subscriber<@NonNull ? super T> a) {
+    void drainFused(Subscriber<? super T> a) {
         int missed = 1;
 
         final SpscLinkedArrayQueue<T> q = queue;
@@ -374,7 +374,7 @@ void drain() {
 
         int missed = 1;
 
-        Subscriber<@NonNull ? super T> a = downstream.get();
+        Subscriber<? super T> a = downstream.get();
         for (;;) {
             if (a != null) {
 
@@ -394,7 +394,7 @@ void drain() {
         }
     }
 
-    boolean checkTerminated(boolean failFast, boolean d, boolean empty, Subscriber<@NonNull ? super T> a, SpscLinkedArrayQueue<T> q) {
+    boolean checkTerminated(boolean failFast, boolean d, boolean empty, Subscriber<? super T> a, SpscLinkedArrayQueue<T> q) {
         if (cancelled) {
             q.clear();
             downstream.lazySet(null);
@@ -475,7 +475,7 @@ public void onComplete() {
     }
 
     @Override
-    protected void subscribeActual(Subscriber<@NonNull ? super T> s) {
+    protected void subscribeActual(Subscriber<? super T> s) {
         if (!once.get() && once.compareAndSet(false, true)) {
 
             s.onSubscribe(wip);
diff --git a/src/main/java/io/reactivex/rxjava3/subscribers/SafeSubscriber.java b/src/main/java/io/reactivex/rxjava3/subscribers/SafeSubscriber.java
index 8556d847ba..f66c34b9b9 100644
--- a/src/main/java/io/reactivex/rxjava3/subscribers/SafeSubscriber.java
+++ b/src/main/java/io/reactivex/rxjava3/subscribers/SafeSubscriber.java
@@ -28,7 +28,7 @@
  *
  * @param <T> the value type
  */
-public final class SafeSubscriber<T> implements FlowableSubscriber<T>, Subscription {
+public final class SafeSubscriber<@NonNull T> implements FlowableSubscriber<T>, Subscription {
     /** The actual Subscriber. */
     final Subscriber<? super T> downstream;
     /** The subscription. */
diff --git a/src/test/java/io/reactivex/rxjava3/validators/NonNullMethodTypeArgumentCheck.java b/src/test/java/io/reactivex/rxjava3/validators/NonNullMethodTypeArgumentCheck.java
new file mode 100644
index 0000000000..f0abb5b23e
--- /dev/null
+++ b/src/test/java/io/reactivex/rxjava3/validators/NonNullMethodTypeArgumentCheck.java
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2016-present, RxJava Contributors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is
+ * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
+ * the License for the specific language governing permissions and limitations under the License.
+ */
+
+package io.reactivex.rxjava3.validators;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.*;
+import java.nio.file.Files;
+import java.util.*;
+
+import org.junit.Test;
+
+import io.reactivex.rxjava3.core.*;
+import io.reactivex.rxjava3.core.Observable;
+import io.reactivex.rxjava3.parallel.ParallelFlowable;
+import io.reactivex.rxjava3.plugins.RxJavaPlugins;
+import io.reactivex.rxjava3.testsupport.TestHelper;
+
+/**
+ * Verify static methods and final methods declaring type arguments
+ * declare {@code @NonNull} for said argument.
+ *
+ */
+public class NonNullMethodTypeArgumentCheck {
+
+    static void process(Class<?> clazz) {
+
+        String className = clazz.getSimpleName();
+        String parentPackage = clazz.getPackage().getName();
+
+        StringBuilder result = new StringBuilder();
+        int count = 0;
+
+        try {
+            File f = TestHelper.findSource(className, parentPackage);
+
+            try (BufferedReader in = Files.newBufferedReader(f.toPath())) {
+                int lineCount = 1;
+                String line = null;
+
+                while ((line = in.readLine()) != null) {
+                    line = line.trim();
+
+                    if (!line.contains(" to(")) {
+                        if (line.startsWith("public static <") || line.startsWith("public final <")) {
+
+                            for (String ta : parseTypeArguments(line)) {
+                                if (!ta.startsWith("@NonNull") && !ta.startsWith("@Nullable")) {
+                                    result.append("Missing annotation on argument ").append(ta).append("\r\nat ")
+                                    .append(parentPackage).append(".").append(className).append(".method(")
+                                    .append(className).append(".java:").append(lineCount).append(")\r\n");
+                                    count++;
+                                }
+                            }
+                        }
+                    }
+                    lineCount++;
+                }
+            }
+        } catch (Exception ex) {
+            throw new RuntimeException(ex);
+        }
+
+        if (count != 0) {
+            throw new IllegalArgumentException("Found " + count + " cases\r\n" + result.toString());
+        }
+    }
+
+    static List<String> parseTypeArguments(String line) {
+        List<String> result = new ArrayList<>();
+        int offset = line.indexOf("<");
+        int c = 1;
+        int i = offset + 1;
+        int j = i;
+        for (; i < line.length(); i++) {
+            if (line.charAt(i) == '<') {
+                c++;
+            } else
+            if (line.charAt(i) == '>') {
+                c--;
+                if (c == 0) {
+                    break;
+                }
+            } else
+            if (line.charAt(i) == ',' && c == 1) {
+                result.add(line.substring(j, i).trim());
+                j = i + 1;
+            }
+        }
+        result.add(line.substring(j, i).trim());
+        return result;
+    }
+
+    @Test
+    public void parseTypeArguments() {
+        assertEquals(new ArrayList<>(Arrays.asList("T")), parseTypeArguments("<T>"));
+        assertEquals(new ArrayList<>(Arrays.asList("T", "U")), parseTypeArguments("<T, U>"));
+        assertEquals(new ArrayList<>(Arrays.asList("T", "Flowable<U>")), parseTypeArguments("<T, Flowable<U>>"));
+        assertEquals(new ArrayList<>(Arrays.asList("T", "Flowable<U, V>")), parseTypeArguments("<T, Flowable<U, V>>"));
+    }
+
+    @Test
+    public void flowable() {
+        process(Flowable.class);
+    }
+
+    @Test
+    public void observable() {
+        process(Observable.class);
+    }
+
+    @Test
+    public void maybe() {
+        process(Maybe.class);
+    }
+
+    @Test
+    public void single() {
+        process(Single.class);
+    }
+
+    @Test
+    public void completable() {
+        process(Completable.class);
+    }
+
+    @Test
+    public void parallel() {
+        process(ParallelFlowable.class);
+    }
+
+    @Test
+    public void plugins() {
+        process(RxJavaPlugins.class);
+    }
+}
diff --git a/src/test/java/io/reactivex/rxjava3/validators/SourceAnnotationCheck.java b/src/test/java/io/reactivex/rxjava3/validators/SourceAnnotationCheck.java
index ee04efa28c..dfa4aea548 100644
--- a/src/test/java/io/reactivex/rxjava3/validators/SourceAnnotationCheck.java
+++ b/src/test/java/io/reactivex/rxjava3/validators/SourceAnnotationCheck.java
@@ -385,7 +385,9 @@ else if (skippingDepth == 0) {
 
             for (String typeName : TYPES_REQUIRING_NONNULL_TYPEARG) {
                 String pattern = typeName + "<?";
-                if (line.contains(pattern)) {
+                String patternRegex = ".*" + typeName + "\\<\\? (extends|super) " + COMMON_TYPE_ARG_NAMES + "\\>.*";
+                if (line.contains(pattern) && !line.matches(patternRegex)) {
+
                     errorCount++;
                     errors.append("L")
                     .append(j)
@@ -402,6 +404,45 @@ else if (skippingDepth == 0) {
                     ;
                 }
             }
+            for (String typeName : TYPES_FORBIDDEN_NONNULL_TYPEARG) {
+                String patternRegex = ".*" + typeName + "\\<@NonNull (\\? (extends|super) )?" + COMMON_TYPE_ARG_NAMES + "\\>.*";
+
+                if (line.matches(patternRegex)) {
+                    errorCount++;
+                    errors.append("L")
+                    .append(j)
+                    .append(" : @NonNull type argument should be on the arg declaration ")
+                    .append(typeName)
+                    .append("\r\n")
+                    .append(" at ")
+                    .append(fullClassName)
+                    .append(".method(")
+                    .append(f.getName())
+                    .append(":")
+                    .append(j + 1)
+                    .append(")\r\n")
+                    ;
+                }
+            }
+
+            for (String typeName : TYPES_REQUIRING_NONNULL_TYPEARG_ON_FUNC) {
+                if (line.matches(".*Function[\\d]?\\<.*, (\\? (extends|super) )?" + typeName + ".*")) {
+                    errorCount++;
+                    errors.append("L")
+                    .append(j)
+                    .append(" : Missing @NonNull type argument annotation on Function argument ")
+                    .append(typeName)
+                    .append("\r\n")
+                    .append(" at ")
+                    .append(fullClassName)
+                    .append(".method(")
+                    .append(f.getName())
+                    .append(":")
+                    .append(j + 1)
+                    .append(")\r\n")
+                    ;
+                }
+            }
         }
 
         if (errorCount != 0) {
@@ -445,6 +486,16 @@ else if (skippingDepth == 0) {
     );
 
     static final List<String> TYPES_REQUIRING_NONNULL_TYPEARG = Arrays.asList(
-            "Iterable", "Stream", "Publisher", "Subscriber", "Processor"
+            "Iterable", "Stream", "Publisher", "Processor", "Subscriber", "Optional"
     );
+    static final List<String> TYPES_FORBIDDEN_NONNULL_TYPEARG = Arrays.asList(
+            "Iterable", "Stream", "Publisher", "Processor", "Subscriber", "Optional"
+    );
+
+    static final List<String> TYPES_REQUIRING_NONNULL_TYPEARG_ON_FUNC = Arrays.asList(
+            "Iterable", "Stream", "Publisher", "Processor", "Subscriber", "Optional",
+            "Observer", "SingleObserver", "MaybeObserver", "CompletableObserver"
+    );
+
+    static final String COMMON_TYPE_ARG_NAMES = "([A-Z][0-9]?|TOpening|TClosing|TLeft|TLeftEnd|TRight|TRightEnd)";
 }