`EclipseJavaCompiler` does not respect `CompilerConfiguration.sourceFiles`, leading to `FilerException: Source file already created` on `mvn compile` without `clean` when e.g. mapstruct is involved

[famod]

Details: #231 (comment)

This aims at doing the first step; making EclipseJavaCompiler use AbstractCompiler.getSourceFiles(CompilerConfiguration) instead of it's own (faulty) logic.

The second step of figuring out what to do (also for javac!) when no explicit sourceFiles are present is not part of this issue.

[famod]

Thanks @olamy! It would be nice to have a release with this (and the updated ECJ dependency).