fix: disable stream for helloworld example, since it do not support

[vincent-pli]

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Fixes #<issue_number_goes_here> 🦕
The helloworld example do not act as stream enable, so I get exception

object async_generator can't be used in 'await' expression

when I try to invoke client.send_message_streaming

[kthota-g]

@vincent-pli I have to revert this PR. Can you please let me know where you are seeing this error?

Invoking message/stream request should the string hello world over SSE.

[vincent-pli]

@kthota-g
I have not dig too much into the root cause, but when the streaming is enabled in the card in hello world example, I get the error when I try to await client.send_message_streaming(request), see the draft code below (not finished yet)
https://github.com/vincent-pli/a2a-agent-mcpserver-generator/blob/a526e7a60d9fb62a2e93810486a9080979c5a932/src/a2a_agent_mcpserver_generator/server_generator.py#L132

[kthota-g]

@vincent-pli send_message_streaming returns an AsyncGenerator, which is not awaitable.

Here is an example for how you can process the response - https://github.com/google/a2a-python/blob/53a58611b32bc3ae01adba432463d1d5cab95f09/examples/helloworld/test_client.py#L33

[vincent-pli]

You are right, my mistake, thanks a lot

[Linux2010]

However, in the invoke method of the HelloWorldAgent, the characteristics of streaming cannot be well demonstrated. Because in this example, both SendStreamingMessageRequest and send_message use the invoke method, lacking distinctiveness.

https://github.com/google/a2a-python/blob/53a58611b32bc3ae01adba432463d1d5cab95f09/examples/helloworld/agent_executor.py#11

@vincent-pli send_message_streaming returns an AsyncGenerator, which is not awaitable.

Here is an example for how you can process the response -

https://github.com/google/a2a-python/blob/53a58611b32bc3ae01adba432463d1d5cab95f09/examples/helloworld/test_client.py#L33