Only support Java 21 build

[jonesbusy]

Only support Java 21 build

Testing done

mvn clean install and CI

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

[jonesbusy]

Weird still some issues

i.j.t.p.core.impl.MavenInvoker # Caused by: java.lang.UnsupportedClassVersionError: io/jenkins/tools/pluginmodernizer/core/recipes/AddDetachedPluginDependency has been compiled by a more recent version of the Java Runtime (class file version 65.0), this version of the Java Runtime only recognizes class file versions up to 61.0 

There is still some Java 17 somewhere

[jonesbusy]

Oh I see I miss

// Minimum JDK to run openrewrite
plugin.withJDK(JDK.JAVA_17);

Perhaps it should be a boolean on the JDK class instead of hardcoded on the code

[jonesbusy]

Should be better with 62a23eb

[gounthar]

Thanks!