Java 21 was released Sep 19, 2023. We would like the most used plugins to be compiled and tested with Java 21.

The acceptance test harness and plugin bill of materials tests are already passing with Java 21. This is a further step to improve plugin readiness for use with Java 21 and for development with Java 21.

I found workarounds for most of the issues I faced when updating this plugin so it could be compiled with Java 21.
I still have a problem with one bug Spotbug detected:

[ERROR] Medium: Unconditional wait in be.certipost.hudson.plugin.SCPRepositoryPublisher.perform(AbstractBuild, Launcher, BuildListener) [be.certipost.hudson.plugin.SCPRepositoryPublisher] At SCPRepositoryPublisher.java:[line 220] UW_UNCOND_WAIT

You can see my attempts there: https://github.com/gounthar/scp-plugin/tree/jdk21 .

Could basil please have a look?

Thanks in advance.