Make Java Platform available on non-java Gradle Projects

[lkishalmi]

This is a workaround. It enables non-java project (root project, or others) to have a Java Platform specified and used during project discovery.

This should be provided by the base Gradle Project support, not the Gradlle Java Project support, but that's for the future.

[lkishalmi]

FYI: The platform customizer is already always enabled.

[sdedic]

While I think this is fine as a workaround, I have some mixed feelings in general about more and more java-related services exposed on generic root projects - see JavaCompilerProcessorFactory, JPDAProcessorFactory: they will now apply to (e.g.) C++ Gradle builds as well.

Maybe some other approach (or registration mechanism) is needed for umbrella / parent / root projects in this case ?

[lkishalmi]

@sdedic I share your feelings. I took the plugin based ProjectService registration from Maven, where it was based on the packaging type. The multi-project Gradle projects were just started to take off and usually even with that the root project had the java plugin applied on most projects I've seen.

If you have ideas, let's start a discussion. I'm open to change. Though now with the new native interfaces in Java, I'd expect more mixed languages project, where one sub-project is a C library, then the next one is a Java. You could expect a JavaExec task show up anywhere in debug mode, or get some stacktrace here and there.

I could imagine, that most of these services would be registered globally. Though the output processors could be dynamic, as we can get some info from the task being executed...

Regarding this JavaPlatformProviderImpl. It shall be in the Gradle Project Support. Also this setting shall be taken from the root project. That's a medium change for NB17.