diff --git a/modules/cache-common/src/main/java/org/opensearch/cache/common/tier/TieredSpilloverCache.java b/modules/cache-common/src/main/java/org/opensearch/cache/common/tier/TieredSpilloverCache.java
index 0442a7d35ebf6..cab05732ba1c4 100644
--- a/modules/cache-common/src/main/java/org/opensearch/cache/common/tier/TieredSpilloverCache.java
+++ b/modules/cache-common/src/main/java/org/opensearch/cache/common/tier/TieredSpilloverCache.java
@@ -236,10 +236,10 @@ static class ConcatenatedIterables<K> implements Iterable<K> {
             this.iterables = iterables;
         }
 
-        @SuppressWarnings({ "rawtypes", "unchecked" })
+        @SuppressWarnings({ "unchecked" })
         @Override
         public Iterator<K> iterator() {
-            Iterator<K>[] iterators = (Iterator<K>[]) new Iterator[iterables.length];
+            Iterator<K>[] iterators = (Iterator<K>[]) new Iterator<?>[iterables.length];
             for (int i = 0; i < iterables.length; i++) {
                 iterators[i] = iterables[i].iterator();
             }
diff --git a/modules/cache-common/src/test/java/org/opensearch/cache/common/tier/MockDiskCache.java b/modules/cache-common/src/test/java/org/opensearch/cache/common/tier/MockDiskCache.java
index 2a3b1caf73732..548c5d846dda5 100644
--- a/modules/cache-common/src/test/java/org/opensearch/cache/common/tier/MockDiskCache.java
+++ b/modules/cache-common/src/test/java/org/opensearch/cache/common/tier/MockDiskCache.java
@@ -81,12 +81,7 @@ public void invalidateAll() {
 
     @Override
     public Iterable<K> keys() {
-        return new Iterable<K>() {
-            @Override
-            public Iterator<K> iterator() {
-                return new CacheKeyIterator<>(cache, removalListener);
-            }
-        };
+        return () -> new CacheKeyIterator<>(cache, removalListener);
     }
 
     @Override
@@ -169,11 +164,11 @@ public Builder<K, V> setValueSerializer(Serializer<V, byte[]> valueSerializer) {
      * @param <K> Type of key
      * @param <V> Type of value
      */
-    class CacheKeyIterator<K, V> implements Iterator<K> {
+    static class CacheKeyIterator<K, V> implements Iterator<K> {
         private final Iterator<Map.Entry<K, V>> entryIterator;
         private final Map<K, V> cache;
         private final RemovalListener<K, V> removalListener;
-        private K lastKey;
+        private K currentKey;
 
         public CacheKeyIterator(Map<K, V> cache, RemovalListener<K, V> removalListener) {
             this.entryIterator = cache.entrySet().iterator();
@@ -192,19 +187,19 @@ public K next() {
                 throw new NoSuchElementException();
             }
             Map.Entry<K, V> entry = entryIterator.next();
-            lastKey = entry.getKey();
-            return lastKey;
+            currentKey = entry.getKey();
+            return currentKey;
         }
 
         @Override
         public void remove() {
-            if (lastKey == null) {
+            if (currentKey == null) {
                 throw new IllegalStateException("No element to remove");
             }
-            V value = cache.get(lastKey);
-            cache.remove(lastKey);
-            this.removalListener.onRemoval(new RemovalNotification<>(lastKey, value, RemovalReason.INVALIDATED));
-            lastKey = null;
+            V value = cache.get(currentKey);
+            cache.remove(currentKey);
+            this.removalListener.onRemoval(new RemovalNotification<>(currentKey, value, RemovalReason.INVALIDATED));
+            currentKey = null;
         }
     }
 }