Java A2A Agents cannot be accessed Using Python ADK RemoteA2aAgent

### What happened?

I tested this with several Java agents such as the Weather Agent and Content Writer Agent. It appears that all Java agents exposed via A2A fail to return responses correctly when accessed through ADK RemoteA2aAgent.

Steps to Reproduce:

1) Run any Java agent (e.g., Content Editor Agent).

2) Create a simple agent using ADK:
`root_agent = RemoteA2aAgent(
name="remote_agent",
description="Helpful assistant to write content",
agent_card=f"http://localhost:10003/{AGENT_CARD_WELL_KNOWN_PATH}",
)
`

3) Run **adk web** , select the remote_agent and try to chat with the agent.
- The response does not appear in the UI.

### Relevant log output

```shell

```

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