support JDK21 JVM and Migration

[nagkumar]

JDK 21 support as it currently supports only JDK 17

[timtebeek]

Hi @nagkumar ! We're tracking support for migrating to Java 21 in this issue:

• Feature request: recipe for migrating to Java 21 rewrite-migrate-java#305

I hope you don't mind me closing this issue, as there's a bit more detail in that other one already.

Thanks for the suggestion though; be sure to watch that other issue for progress.

[nagkumar]

My Observation is it is not accepting JDK 21 as runtime used to run the gradle task rewriteRun, not jdk21, jdk20, jdk19 as gradle runtime is not supported, only jdk11 to jdk 17 is supported

[timtebeek]

Correct; as pointed out in that other issue we're waiting for these blockers to be cleared before we can continue:

• Support running with Java 21 gradle/gradle#25574
• https://docs.gradle.org/8.4-rc-1/release-notes.html

Only then can we get started on a Java 21 specific parser, similar to the Java 8, 11 and 17 parsers in OpenRewrite/rewrite, which will then unlock support for running on Java 21 as well.