Fix ProtoCoder NoSuchMethodException

[Suvrat1629]

Please add a meaningful description for your change here

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Handles NoSuchMethodException in ProtoCoder.getParser() when getDefaultInstance() is unavailable by adding a fallback to instantiation.
Addresses #19713

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[gemini-code-assist]

Summary of Changes

Hello @Suvrat1629, 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 significantly improves the robustness of ProtoCoder by addressing a potential NoSuchMethodException during parser initialization. It introduces a fallback to direct instantiation when getDefaultInstance() is absent and adds clearer error messages for unsupported Protobuf message types, ensuring broader compatibility and better developer experience.

Highlights

• Robust Parser Initialization: The ProtoCoder.getParser() method has been enhanced to gracefully handle scenarios where the getDefaultInstance() method is not available on a Protobuf message class. It now includes a fallback mechanism to instantiate the message directly using its no-argument constructor.
• Improved Error Handling: Specific IllegalArgumentException messages have been added for unsupported cases, such as attempting to use ProtoCoder with the raw com.google.protobuf.Message interface or abstract message classes, guiding users to use concrete Protobuf-generated classes.
• New Test Cases: Comprehensive unit tests have been introduced to validate the new fallback logic and error handling, covering cases for raw Message interfaces, generated classes, and abstract classes.

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[Suvrat1629]

/gemini review

[gemini-code-assist]

Code Review

This pull request enhances ProtoCoder by adding a fallback mechanism to handle cases where getDefaultInstance() is unavailable, improving its robustness. It also correctly disallows the use of the raw Message interface. The accompanying tests are a good start, but I've identified a duplicated test case and another that could be improved for clarity and correctness. My review provides specific suggestions to address these points in the test suite.

[Suvrat1629]

/gemini review

[gemini-code-assist]

Code Review

This pull request addresses an issue where ProtoCoder would fail with a NoSuchMethodException for Protobuf message classes that do not have a getDefaultInstance() method. The fix introduces a fallback mechanism to instantiate the class using its no-arg constructor, which is a great improvement in flexibility. The error handling has also been made more specific and informative. The accompanying tests cover several new failure scenarios, but I've noted a gap in testing the new successful fallback path, which would be valuable to add.

[github-actions]

Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

[Suvrat1629]

assign set of reviewers

[github-actions]

Assigning reviewers:

R: @chamikaramj for label java.

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[Suvrat1629]

@robertwb I had lost track of the pr but I have reopened it now. As far as I see the failing test does not concern the files I have changed. If you could please take a look at this pr.
Thank you!

[github-actions]

Reminder, please take a look at this pr: @chamikaramj

[github-actions]

Assigning new set of reviewers because Pr has gone too long without review. If you would like to opt out of this review, comment assign to next reviewer:

R: @ahmedabu98 for label java.

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[github-actions]

Reminder, please take a look at this pr: @ahmedabu98

[github-actions]

Assigning new set of reviewers because Pr has gone too long without review. If you would like to opt out of this review, comment assign to next reviewer:

R: @kennknowles for label java.

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