[cxf] add support for Swagger2

[fwermelskirchen]

to fix #3668 based on #17696

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.
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• 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)
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[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/17911877352/job/50959082391?pr=22010

please follow step 3 to update the samples

[wing328]

tested locally and the result is good

[INFO] Running org.openapitools.api.PetApiTest
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.661 s -- in org.openapitools.api.PetApiTest
[INFO] Running org.openapitools.api.StoreApiTest
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.011 s -- in org.openapitools.api.StoreApiTest
[INFO] Running org.openapitools.api.UserApiTest
[INFO] Tests run: 8, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.057 s -- in org.openapitools.api.UserApiTest
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 20, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO]
[INFO] --- jar:3.3.0:jar (default-jar) @ openapi-jaxrs-client ---
[INFO] Building jar: C:\Users\wing3\AppData\Local\Temp\jaxrs\target\openapi-jaxrs-client-1.0.0.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  5.987 s
[INFO] Finished at: 2025-09-24T15:14:01+08:00

i'll add some tests later with another pr

thanks again for the PR