A follow-up PR to #22726 (update workflow, samples)

[wing328]

a follow-up pr to #22726

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
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Summary by cubic

Streamlined the Spring HTTP Interface OAuth sample to a minimal Petstore “addPet” client and wired it into the JDK17 workflow to speed up generation and CI validation.

• Refactors

  • Switched generator input to modules/openapi-generator/src/test/resources/3_0/petstore-addpet-only.yaml.
  • Renamed sample artifact to spring-http-interface-oauth-petstore.
  • Pruned generated code to only PetApi and related DTOs; removed unused APIs/models and beans.
  • Updated PetApi.addPet to return ResponseEntity<PetDto> and accept application/json and application/xml.
  • Changed PetDto.photoUrls from Set to List; made CategoryDto.name nullable and removed default; updated model docs.
  • Simplified README and allowed it to be regenerated by removing the ignore rule.

• CI

  • Added samples/client/petstore/spring-http-interface-oauth/** to the Spring JDK17 workflow triggers and build matrix.

^{Written for commit ae3f890. Summary will update on new commits. Review in cubic}