fix: clear awaitingFinalEvent flag on queue when timeout reached

The timeout logic was setting a local variable to false, but the next
iteration would read true again from queue.isAwaitingFinalEvent(),
causing the grace period to never start. Added clearAwaitingFinalEvent()
method to ChildQueue to properly clear the flag on the queue itself.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: kabir

server-common/src/main/java/io/a2a/server/events/EventConsumer.java

@@ -114,7 +114,11 @@ public Flow.Publisher<EventQueueItem> consumeAll() {
                                 if (pollTimeoutsWhileAwaitingFinal >= MAX_POLL_TIMEOUTS_AWAITING_FINAL) {
                                     LOGGER.debug("Waited {} timeouts for final event but it hasn't arrived - proceeding with normal timeout logic (queue={})",
                                         pollTimeoutsWhileAwaitingFinal, System.identityHashCode(queue));
-                                    awaitingFinal = false; // Give up waiting, let normal timeout logic proceed
+                                    // Clear the flag on the queue itself, not just the local variable
+                                    if (queue instanceof EventQueue.ChildQueue) {
+                                        ((EventQueue.ChildQueue) queue).clearAwaitingFinalEvent();
+                                    }
+                                    awaitingFinal = false; // Also update local variable for this iteration
                                 }
                             } else {
                                 pollTimeoutsWhileAwaitingFinal = 0; // Reset when event arrives or queue not awaiting

server-common/src/main/java/io/a2a/server/events/EventQueue.java

@@ -820,6 +820,15 @@ void expectFinalEvent() {
             LOGGER.debug("ChildQueue {} now awaiting final event", System.identityHashCode(this));
         }
 
+        /**
+         * Called by EventConsumer when it has waited too long for the final event.
+         * This allows normal timeout logic to proceed if the final event never arrives.
+         */
+        void clearAwaitingFinalEvent() {
+            awaitingFinalEvent = false;
+            LOGGER.debug("ChildQueue {} cleared awaitingFinalEvent flag (timeout)", System.identityHashCode(this));
+        }
+
         @Override
         public void close() {
             close(false);