GSIP 232 - Upgrade GeoServer and GeoWebCache Build to Java 17

Hi all,

As mentioned in Jody’s “GS3 Milestone 1 Updates” topic, we’re ramping up on the GeoServer crowdfunding work.

A pre-requisite for it is establishing Java 17 as the baseline version for the build, hence I’m making this proposal to cover both GeoServer and GeoWebCache:

It goes in tandem with the GeoTools change proposal here: Migrate GeoTools to Java 17 · geotools/geotools Wiki · GitHub

The preliminary work is done and validated. What remains is to make the Error Prone plugin happy as is reports a lot more issues.

Please review and share your feedback.

Thanks,

Gabe