Consider moving to a higher Java version

[gouttegd]

Currently, Protégé is developed, tested, and shipped with Java 11. It has been tested to work with Java versions up to 16, but there are known issues with Java 17 and higher.

Looking at Adoptium’s roadmap, their Java 11 distribution will be supported until “at least October 2027”, so we have some margins to migrate to a higher version, but it would be best not to wait until the last moment…

As for which version should we migrate to: it seems that Java 17 will not be supported for much longer than Java 11 (also “at least October 2027”), so it may not be worth it. We should probably jump straight to Java 21 instead (supported until at least end of 2029).

[Freso]

#822 should maybe be closed in favour of this, then. (Or maybe just closed, if you’re already working off of 11.)