chore: Generate grpc classes from protobuf in build

[kabir]

Description

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Fixes #<issue_number_goes_here> 🦕

[gemini-code-assist]

Summary of Changes

Hello @kabir, 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!

I've updated the project's build configuration to automatically generate gRPC classes from our protobuf definitions. This change integrates the protobuf compilation directly into the Maven build process, ensuring that our Java gRPC stubs and messages are always in sync with the latest .proto files. This automation streamlines development by reducing manual steps and potential inconsistencies.

Highlights

• Automated gRPC Class Generation: Configured Maven to automatically generate gRPC Java classes from protobuf definitions using protobuf-maven-plugin.
• Maven Dependency Updates: Updated pom.xml files to include necessary plugin versions and dependencies for protobuf and gRPC generation.
• Generated Code Refinement: Removed redundant json_name annotations from numerous generated Java gRPC files, streamlining the generated code.
• GRPC Service Stub Integration: Enabled the @javax.annotation.Generated annotation in A2AServiceGrpc.java, indicating proper integration of generated code.

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[gemini-code-assist]

Code Review

This pull request sets up the generation of gRPC classes from protobuf definitions during the build process, which is a great improvement for maintainability.

My main feedback is about the configuration of the protobuf-maven-plugin. It's currently configured to write generated files into the src/main/java directory, and these generated files are included in this pull request. It's a best practice to generate code into a build directory (e.g., inside target/) and not commit generated files to version control. This prevents merge conflicts in generated code and ensures that the Java classes are always in sync with the .proto definitions.

I've left a specific suggestion on spec-grpc/pom.xml to adjust the output directory and enable clearing it on each build. After applying this change, you should remove the generated .java files from this PR and add them to your .gitignore file.

The removal of the redundant json_name attributes from the proto definitions is a good cleanup.

[gemini-code-assist]

It's great that you're setting up the protobuf compilation in the build. However, the current configuration has a couple of issues that could lead to problems down the line:

1. Output Directory: Generating code directly into src/main/java mixes generated code with manually written source code. This is generally discouraged as it makes the project harder to navigate and maintain. A better practice is to generate code into a directory within target, for example ${project.build.directory}/generated-sources/protobuf/java. The protobuf-maven-plugin will automatically add this directory as a source root for compilation.

2. Clearing Output Directory: clearOutputDirectory is set to false. This is risky because if you remove a message or a field from a .proto file, the old generated Java files won't be deleted. This can lead to stale code and hard-to-debug compilation or runtime errors. It's much safer to set this to true.

By making these changes, you also wouldn't need to check the generated Java files into source control, which is the standard practice. The build process would be responsible for generating them on-the-fly. This avoids merge conflicts in generated files and ensures they are always up-to-date with the .proto definitions.

                                <outputDirectory>${project.build.directory}/generated-sources/protobuf/java</outputDirectory>
                                <clearOutputDirectory>true</clearOutputDirectory>

[kabir]

The plugin is quite flaky. I tried the suggestion, but it failed. Probably because clearOutputDirectory removes the files from the 'compile' goal before it does the 'compile-custom' goal.

So I think we should commit the files.

To work around the 'stale files' issue I added the maven-clean-plugin to the 'proto-compile' profile, and remove all the generated files before regenerating them.

[fjuma]

@kabir Just to check, which version of a2a.proto is this? v0.2.6?

[kabir]

@fjuma I used 0.2.5 - were we using 0.2.6 before?

[fjuma]

@kabir Looks good. Would it make sense to add something in the README or a comment somewhere on how to generate the files?