Please check back with @5iver, he said to use OpenJDK11 with jython 2.7.2 with no problems.
I didn’t closely follow this nrjserial stuff, does 2.5 still use some old version to conflict with Java 11 because of core freeze ? What should I mention in the announcement post to NOT open as threads because it is a known issue ? Any serial related exception ?
[ if that means you cannot run anything-to-use-serial because of that I’d put a big question mark behind the core freeze as it would IMHO mean only very few people can go Java 11 today but everyone has to use it right from the start with OH3 ]