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Contribution guide.

Is your feature request related to a specific problem?

1.Based on the following source code reading, in the logic of converting invocationContext to Message using EventConverter.convertEventsToA2AMessage:

Optional<Message> a2aMessageOpt = com.google.adk.a2a.EventConverter.convertEventsToA2AMessage(invocationContext);

metadata is not assigned. Therefore, will the following code always return a null case:

Map<String, Object> metadata = originalMessage.getMetadata() == null ? Map.of() : originalMessage.getMetadata();

Is it possible to convert invocationContext.session.state to the metadata of the Message, as additional information in the communication protocol between the client agent and the server agent? like this：

2.Multiple agents communicate via the A2A protocol, using a synchronous blocking approach.

Due to the time-consuming nature of this communication, which negatively impacts user experience, it is recommended to replace the synchronous approach with SSE streaming output. Simultaneously, the client should use a pre-implemented streaming HTTP request to establish connections.

Describe the Solution You'd Like

Some of the solution code logic is above.