[Java] (JPMS) Add a maven plugin for compiling modules while retaining JDK8 support #39134
Description
Describe the enhancement requested
The traditional method of compiling modules is to use -release 9 to compile everything in the module, then recompile everything except module-info.java using release 8. This conflicts with the use of Unsafe in JDK8.
Instead, we can write a plugin which does a purely syntactic compilation of module-info.java files.
Component(s)
Java