fix: mark ModelConvertor parameters and returns as non-null (#2507)

[vikas-prasad-cx]

Summary

• Mark ModelConvertor with @NullMarked and document that method parameters/returns are never null (use empty Optional for no prior output).
• Align AbstractTrivialModelConvertor with the same contract via runtime Objects.requireNonNull checks, removing the previous null-tolerant modelOutput path.
• Add unit tests covering the annotation contract and null-argument rejection.

Fixes #2507

Test plan

• ./mvnw test -pl service/definition -Dtest=ModelConvertorNullabilityTest
• ./mvnw test -pl service/quarkus/deployment -Dtest=AbstractTrivialModelConvertorTest
• ./mvnw test -pl service/definition,service/quarkus/deployment (40 tests passed)
• CI checks on this PR

Made with Cursor

[vikas-prasad-cx]

Hi — gentle ping on this PR when you have a chance. Happy to address any feedback. CI may still need first-time contributor workflow approval. Thanks!

[triceo]

Hello @vikas-prasad-cx - we are aware of your PR and we will get to it when time permits.
Thank you for your contribution, and for your patience.

[rsynek]

@vikas-prasad-cx Thanks for your contribution!

Also, my apologies for the delay with reviewing your PR.

I left one comment inline, plus, in order to declare non-null parameters of the ModelConvertor methods we must ensure that the caller never passes nulls there.

In case we don't have the ModelConfig instance, there is empty factory method.

[vikas-prasad-cx]

@rsynek Thank you for the review, and no worries about the delay.

Addressed in 8895be2:

• Removed ModelConvertorNullabilityTest as requested.
• SolverWorker now passes ModelConfig.empty() when no config is available, so ModelConvertor callers never hand in a null ModelConfig. The existing AbstractTrivialModelConvertor null-checks and the ModelConfig.empty() happy-path test are unchanged.

Happy to adjust further if needed.

[rsynek]

@rsynek Thank you for the review, and no worries about the delay.

Addressed in 8895be2:

• Removed ModelConvertorNullabilityTest as requested.
• SolverWorker now passes ModelConfig.empty() when no config is available, so ModelConvertor callers never hand in a null ModelConfig. The existing AbstractTrivialModelConvertor null-checks and the ModelConfig.empty() happy-path test are unchanged.

Happy to adjust further if needed.

Thank you, looks very good now! I will take care of the CI checks and let you if any further change is needed.