[kotlin-server][Java][JAX-RS] Fix path shadowing (#23414)

[feczkob]

Fixes #23414.

The generator now tracks all resource paths across tags during code generation. Before applying a common @Path prefix to an API class, it checks if that prefix would "shadow" (intercept) routes belonging to other tags - if so, it keeps the full paths on each method instead.

Could you take a look, please?

@karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03) @stefankoppier (2022/06) @e5l (2024/10) @dennisameling (2026/02) and @lbilger

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Summary by cubic

Fixes path shadowing in Java JAX-RS and Kotlin jaxrs-spec generators by skipping a class-level @Path when it would hide routes from other tags, keeping all endpoints reachable. Fixes #23414.

• Bug Fixes
  • Collect all resource paths across tags and skip commonPath if it would shadow another tag’s route.
  • Add a cross-tag shadow check in AbstractJavaJAXRSServerCodegen during jaxrsPostProcessOperations; include helpers to compute/apply common path.
  • Mirror the logic in KotlinServerCodegen for the jaxrs-spec library; other Kotlin libraries remain unchanged.
  • Add regression tests and sample spec: JavaJaxrsBaseTest#testCommonPathDoesNotShadowOtherTags, KotlinServerCodegenTest#testCommonPathDoesNotShadowOtherTags_jaxrsSpec, src/test/resources/3_0/issue_23414.yaml.
  • Regenerate samples to reflect the new path handling (e.g., JAX-RS FakeApi now uses @Path("") with full method paths; add Kotlin Ktor sample files AppMain.kt and Configuration.kt).

^{Written for commit 0986dc7. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

No issues found across 5 files

_{Re-trigger cubic}

[feczkob]

Global path registry.

[feczkob]

Every time an operation is assigned to a tag, its full resource path is added to the global path registry.

[feczkob]

Before applying a common path prefix to a tag's API class, the generator checks shadowing.

[wing328]

@feczkob thanks for the PR

@lbilger I wonder if you can test/review this change to confirm whether it addresses the issue #23414

git checkout -b feczkob-fix/23414-path-shadowing master
git pull https://github.com/feczkob/openapi-generator.git fix/23414-path-shadowing

[wing328]

@feczkob are you using this fix in production and confirm it works for your use cases?

[feczkob]

@wing328 no, the bug appears only in an edge case. However, I verified the change on the reproducer of @lbilger and the tests pass. I also took a look at the generated classes and they are as expected. Not sure whether we should wait more for his feedback or we can rather proceed with the merge.

[lbilger]

Hi @feczkob , thanks a lot for fixing this! Unfortunately, I can't test it at the moment, but it looks good and if you tried with the reproducer, I'm inclined to believe that it works. So thumbs up from me 👍

[feczkob]

@lbilger let's test it when you have some free time, just to be super sure 😄 In the meantime, @wing328 do you want to wait more, or can we proceed with the merge?

[wing328]

Let's give it a try 👍