feat: implement streaming support in to_a2a for issue #4240

[sanjeevamk1]

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Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Closes: SSE Streaming providing to to_a2a #4240

Problem:
For token streaming when adk agent is exposed with to_a2a

Solution:
Added streaming_mode in to_a2a to select streaming while exposing the agent

[gemini-code-assist]

Summary of Changes

Hello @sanjeevamk1, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the to_a2a utility by integrating streaming support, allowing for more dynamic and efficient handling of agent responses. By introducing a StreamingMode and a configurable request converter, users can now specify how data is streamed when an ADK agent is converted into an A2A Starlette application, providing greater flexibility for interactive and real-time agent interactions.

Highlights

• Streaming Mode Introduction: Introduced a new StreamingMode enum to control how agent responses are streamed.
• Configurable Request Converter: Added a new experimental function create_request_converter that allows generating a request converter configured with a specific StreamingMode.
• Streaming Support in to_a2a: The to_a2a utility function now accepts a streaming_mode parameter, enabling the configuration of streaming behavior when converting an ADK agent to an A2A Starlette application.
• Executor Configuration Update: The A2aAgentExecutor within to_a2a is now initialized with an A2aAgentExecutorConfig, which incorporates the streaming-aware request converter.

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[adk-bot]

Response from ADK Triaging Agent

Hello @sanjeevamk1, thank you for creating this PR!

To help reviewers understand and evaluate your contribution, could you please fill out the pull request template in the description? Specifically, please provide the following:

• Link to Issue or Description of Change: Please either link to the relevant issue or provide a description of the problem and your solution.
• Testing Plan: Describe the tests you ran to verify your changes, including any unit tests or manual end-to-end tests.
• Checklist: Please fill out the checklist to confirm you've followed the contribution guidelines.

This information is crucial for an efficient review process. You can find more details in our contribution guide.

Thanks!

[gemini-code-assist]

Code Review

This pull request introduces streaming support for the to_a2a function. The implementation approach is sound, but I've identified a critical issue with a shadowed import that will likely lead to runtime failures. Additionally, there's an opportunity to improve maintainability by addressing significant code duplication in the new request converter. I've also pointed out a minor typo. Please review my comments for details.

[ryanaiagent]

H @sanjeevamk1, Thank you for your contribution! We appreciate you taking the time to submit this pull request. Can you address the comment and also fix the formatting errors before we can proceed with the review. You can use autoformat.sh for formatting errors.