Fix a bug in DefaultPromise.notifyLateListener() where the listener i…

…s not notified

Motivation:

When (listeners == null && lateListeners == null) and (stackDepth >= MAX_LISTENER_STACK_DEPTH), the listener is not notified at all. The discard client does not work.

Modification:

Make sure to submit the notification task.

Result:

The discard client works again and all listeners are notified.

common/src/main/java/io/netty/util/concurrent/DefaultPromise.java

@@ -624,6 +624,7 @@ private void notifyLateListener(final GenericFutureListener<?> l) {
                     } finally {
                         LISTENER_STACK_DEPTH.set(stackDepth);
                     }
+                    return;
                 }
             } else {
                 LateListeners lateListeners = this.lateListeners;
@@ -632,13 +633,14 @@ private void notifyLateListener(final GenericFutureListener<?> l) {
                 }
                 lateListeners.add(l);
                 execute(executor, lateListeners);
+                return;
             }
-        } else {
-            // Add the late listener to lateListeners in the executor thread for thread safety.
-            // We could just make LateListeners extend ConcurrentLinkedQueue, but it's an overkill considering
-            // that most asynchronous applications won't execute this code path.
-            execute(executor, new LateListenerNotifier(l));
         }
+
+        // Add the late listener to lateListeners in the executor thread for thread safety.
+        // We could just make LateListeners extend ConcurrentLinkedQueue, but it's an overkill considering
+        // that most asynchronous applications won't execute this code path.
+        execute(executor, new LateListenerNotifier(l));
     }
 
     protected static void notifyListener(