Migration to Java 11 from Java 8

[chenejac]

Is your feature request related to a problem? Please describe.
Some libraries/dependences require JDK 11+, e.g. Jena 4.

Describe the solution you'd like
Migration to JDK 11 including upgrading some libraries/dependencies if that is needed.

Describe alternatives you've considered
Migration to JDK 17

[michel-heon]

For many of my assignments it is better to work with the new version (11 or 17).
Here is the list of tasks depending on it.
Testing performance of external graph usage
Improvement of communication with external graph
Investigate and specify support for reasoning

and also, all task associated to "Jena TDB"

[michel-heon]

from my point of view, as long as we have to do the work, I think it's better to go directly to Java 17 and thus avoid possible incompatibilities problems that could occur during a future transition from 11 to 17. I'm thinking in particular of the integration of the reasoner whose source code development has been stopped for a few years. It would be a bad thing to lose some developed functionalities because of an incompatibility between version 11 and 17 (or higher)

[michel-heon]

I propose that this task be moved to "jena tdb".

[michel-heon]

@chenejac @wwelling @litvinovg
I just found this document: Oracle JDK Migration Guide
Before going further in the PR's, I propose to review the work already done against this specification
I haven't read the whole thing yet but I think there are some good recommendations on what to do when considering an upgrade to Java11

[chenejac]

It looks as jdeps might be useful in the migration process
https://docs.oracle.com/en/java/javase/11/tools/jdeps.html
https://docs.oracle.com/en/java/javase/11/tools/jdeprscan.html

@michel-heon did you already try to run those checks?