broaden the requestTrace attachment accessor (#1297)

broaden the requestTrace attachment accessor

changelog/@unreleased/pr-1297.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: broaden the requestTrace attachment accessor
+  links:
+  - https://github.com/palantir/tracing-java/pull/1297

tracing-undertow/src/main/java/com/palantir/tracing/undertow/TracingAttachments.java

@@ -38,14 +38,23 @@ public final class TracingAttachments {
      */
     static final AttachmentKey<DetachedSpan> REQUEST_SPAN = AttachmentKey.create(DetachedSpan.class);
 
+    /**
+     * The {@link Detached} trace state which represents the top-level request being processed. This may
+     * be used to apply thread state to code executing outside traced handlers, exchange completion
+     * listeners, for example.
+     */
+    @SuppressWarnings("unchecked")
+    public static final AttachmentKey<Detached> REQUEST_DETACHED_TRACE =
+            (AttachmentKey<Detached>) (AttachmentKey<?>) REQUEST_SPAN;
+
     /**
      * Gets the {@link Detached} trace state which represents the top-level request being processed. This may
      * be used to apply thread state to code executing outside traced handlers, exchange completion
      * listeners, for example.
      */
     @Nullable
     public static Detached requestTrace(HttpServerExchange exchange) {
-        return exchange.getAttachment(REQUEST_SPAN);
+        return exchange.getAttachment(REQUEST_DETACHED_TRACE);
     }
 
     private TracingAttachments() {}

tracing-undertow/src/test/java/com/palantir/tracing/undertow/TracedOperationHandlerTest.java

@@ -201,6 +201,8 @@ public void whenSamplingDecisionHasNotBeenMade_callsSampler() throws Exception {
     public void setsDetachedTrace() throws Exception {
         handler.handleRequest(exchange);
         assertThat(TracingAttachments.requestTrace(exchange)).isNotNull();
+        assertThat(exchange.getAttachment(TracingAttachments.REQUEST_DETACHED_TRACE))
+                .isNotNull();
     }
 
     @Test