[Java] Support Deprecation of Generated enum-classes

[Chrimle]

Adds support for generated enum-classes to be annotated @Deprecated when deprecated: true is set in the OpenAPI-schema, similarly to how it is done when generating classes. Note: this annotation is not applied to inner enum-classes.

Fixes #22311.

OpenAPI Schema:

DeprecatedExampleEnum:
  type: string
  deprecated: true
  enum:
    - ENUM1
    - ENUM2
    - ENUM3

Results in:

/**
 * Gets or Sets DeprecatedExampleEnum
 */
@Deprecated
public enum DeprecatedExampleEnum {
  
  ENUM1("ENUM1"),
  
  ENUM2("ENUM2"),
  
  ENUM3("ENUM3");
  
  // ... unchanged ...
}

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)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

[wing328]

suggestion:

{{#isDeprecated}}
@Deprecated
{{/isDeprecated}}

[Chrimle]

This will result in an empty line, like:

/*
 * javadoc here...
 */
 
 @Deprecated

Also, making a newline between {{/isDeprecated}} and {{#gson}} will always generate another empty line after the deprecated-annotation, or result to 2 empty lines after the javadocs.

Is this OK? (from a Style-Guide perspective)?

[Chrimle]

Hi @wing328, the suggested change has been done, and the updated samples have been committed too. 👍

[Chrimle]

Hello @wing328 !
I have ran /.mvnw clean install and then ./bin/generate-samples.sh ./bin/configs/java*. The updated sample files have been committed to show the diffs.

Personally, with reference to the google-java-format, the new line added to these classes is not conforming to the format.

Is this OK, or should I address this at the same time as your suggestion?

Cheers

[Chrimle]

Will update the other Java templates too.

[Chrimle]

No other files have been updated. Ready for review!

[Chrimle]

Pinging the Java Tech Committee 🔔
@bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @martin-mfg

Hopefully this is how it is intended 🙏

[wing328]

looks good to me. let's give it a try

i'll add a test in another PR

done via #22335