~ fixed a compatibility issue with Java 11
I removed the last bits of Java 15 compiler. Now it only uses Java 8 once again.
Thanks to
XXirs for the notice
Info
However, I will change the Java version to latest, when 1.17 releases, as Java 8 will be unsupported by most software (e.g Paper). Also it is better to use, to get even the most out of the plugins; so keep that in mind!