[JAVA]: Fix unknown property error for gradle build

[HeneryHawk]

If i generate a client for java with the library native, i get the following error when i try to build the client via ./gradlew assemble.

/build.gradle' line: 53
Could not set unknown property 'classifier' for task ':sourcesJar' of type org.gradle.api.tasks.bundling.Jar.

This error can also be reproduced if you use the native Java echo_api client sample.
According to the gradle documentation, the classifier property was removed with the update to Gradle 8.x
See: https://docs.gradle.org/current/userguide/upgrading_version_7.html#abstractarchivetask_api_cleanup

@bbdouglas @Zomzog @lwlee2608 @martin-mfg

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 
  ./bin/generate-samples.sh ./bin/configs/*.yaml
  ./bin/utils/export_docs_generators.sh
  

  (For Windows users, please run the script in Git BASH)
  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.
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[martin-mfg]

Hi @HeneryHawk, thanks for the PR!

May I ask you to apply the same fix for other Java libraries besides native as well?

[HeneryHawk]

Hi @martin-mfg

yes I can do that but can we postpone this to a later PR? We would need the adaptions for native asap...

Regards

[wing328]

@HeneryHawk thanks for the PR.

totally ok to have a separate PR to address similar issue in other build.gradle files.

i'm able to repeat the issue by adding gradle build tests for java native petstore samples via #19951

will get that one merged after merging your fix so that this issue is covered moving forward.

[wing328]

UPDATE: merged #19951 to add tests and sync pom.xml & build.gradle (to fix an issue when useJakartaEe is eanbled)