[kotlin-server][JAX-RS] Fix class names for useTags

[feczkob]

Follow-up of #23379.

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Summary by cubic

Fixes JAX-RS kotlin-server class naming when useTags=false and standardizes @Path generation by computing a class-level common path. useTags now defaults to true, so tags drive class names unless disabled.

• Bug Fixes

  • JAX-RS (jaxrs-spec): compute commonPath for every API class; set class-level @Path to it (empty string for root) and emit method @Path only for sub-resources.
  • When useTags=false, group operations (and class names) by base path (first resource path segment) with fallback to default if empty or templated.

• Refactors

  • Default useTags to true (docs updated; scope clarified to jaxrs-spec), remove useTags from kotlin-server-jaxrs-spec.yaml.
  • Update templates and README to use {{commonPath}}{{path}} and guard method @Path with subresourceOperation.
  • Update tests and regenerated samples to reflect new defaults and paths.

^{Written for commit c3e559b. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 14 files

[feczkob]

I used this repo for reproduction, thanks to @lbilger: https://github.com/lbilger/openapi-generator-path-shadowing-reproducer

JAXRS-SPEC, useTags = true

kotlin-server, JAXRS-SPEC, useTags = true

JAXRS-SPEC, useTags = false

kotlin-server, JAXRS-SPEC, useTags = false

JAXRS-SPEC, no useTags defaults to false

⚠️ kotlin-server, JAXRS-SPEC, no useTags defaults to true

[lbilger]

@feczkob I think I see more or less what you're doing here now. You want to align kotlin-server/jaxrs-spec with the "original" jaxrs-spec. If that is the main goal, the PR mostly achieves it as far as I can see. Only the docs should also state that the useTags parameter is only supported for this library, just like useMutiny already does.

This will however be a breaking change for everyone using this generator/library. Also, it deliberately excludes all the other libraries from using this parameter even though it would be no additional effort to support it for all libraries. So I suggest to at least consider making useTags=true the default, even though it is not completely in line with jaxrs-spec.

[lbilger]

It seems operationIdLowerCase is not set in the useTags=false case - probably because the super method that sets it is never called.

[feczkob]

Nice catch, fixed in c3e559b

[feczkob]

Hey @lbilger, I added a new commit c3e559b with your suggested changes. The default for useTags will be true for kotlin-server with JAXRS-SPEC, and the parent's super method will not be skipped. My goal with this PR was to match the behavior of the Java JAXR-SPEC generator, but it's reasonable to deviate from that to avoid breaking changes.

As for the future steps, I can think of a few:

• make useTags accessible for every kotlin-server generator - should be fairly easy, as you pointed out
• simplify the addOperationToGroup() method of AbstractJavaJAXRSServerCodegen.java to match the one we propose for kotlin-server
• fix the original bug you reported for both generators

When my time permits, I'd pick up the last one in a separate PR, to finally make useTags work as expected, without the path shadowing.