fix(a2a): await enqueue_event calls in agent executors

The enqueue_event coroutine was called without await in the contact
extractor and currency converter executors. This silently dropped
A2A streaming events (artifact, status updates), causing the UI to
never receive agent responses despite the agent processing correctly.

Assisted-By: Claude (Anthropic AI) <noreply@anthropic.com>
Signed-off-by: Paolo Dettori <dettori@us.ibm.com>

Author: pdettori

a2a/a2a_contact_extractor/agent_executor.py

@@ -71,7 +71,7 @@ async def execute(
                 )
 
             if require_user_input:
-                event_queue.enqueue_event(
+                await event_queue.enqueue_event(
                     TaskStatusUpdateEvent(
                         status=TaskStatus(
                             state=TaskState.input_required,
@@ -87,7 +87,7 @@ async def execute(
                     )
                 )
             elif is_task_complete:
-                event_queue.enqueue_event(
+                await event_queue.enqueue_event(
                     TaskArtifactUpdateEvent(
                         append=False,
                         contextId=task.context_id,
@@ -96,7 +96,7 @@ async def execute(
                         artifact=artifact,
                     )
                 )
-                event_queue.enqueue_event(
+                await event_queue.enqueue_event(
                     TaskStatusUpdateEvent(
                         status=TaskStatus(state=TaskState.completed),
                         final=True,
@@ -105,7 +105,7 @@ async def execute(
                     )
                 )
             else:
-                event_queue.enqueue_event(
+                await event_queue.enqueue_event(
                     TaskStatusUpdateEvent(
                         status=TaskStatus(
                             state=TaskState.working,

a2a/a2a_currency_converter/app/agent_executor.py

@@ -51,7 +51,7 @@ async def execute(
         if not task:
             task = new_task(context.message)
             logger.info(f"Created task for message : {context.message}")
-            event_queue.enqueue_event(task)
+            await event_queue.enqueue_event(task)
         updater = TaskUpdater(event_queue, task.id, task.context_id)
         try:
             async for item in self.agent.stream(query, task.context_id):