Require Jenkins 2.479.3 or newer and Jakarta EE 9

[strangelookingnerd]

Require Jenkins 2.479.3 or newer and Jakarta EE 9

Jenkins 2.479.3 provides Jakarta EE 9, Eclipse Jetty 12, Spring Security 6, and Java 17.

• Update plugin pom and baseline
• Cleanup dependencies and use versions provided by bom
• Remove deprecations
• Use Java 17 language features
• Trivial code cleanup

Testing done

mvn clean verify - I had local test failures that I also had without my changes. So not entirely sure if these changes broke something or not. I'd advice that these changes are validated before merging.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[mawinter69]

pom looks good

[mawinter69]

Looks good from pom point of view. The hpi is 2.4MiB and no longer over 12 MiB
Can't judge the other changes

[strangelookingnerd]

@jenkinsci/datadog-plugin-developers Kindly requesting a review.

[afontan]

Hey @strangelookingnerd, thanks for the contribution, but for now, we still want to be compatible with Jenkins 2.361.4. Also, 30%+ of the plugin users are using a lower version of Jenkins than 2.479.3, although some of them are not keeping the plugin up-to-date. We will discuss internally when we will be ready to do this update.