Getting more information on gradle compileJava annotation processor warning

I have a java project that uses gradle, and when I try to compile it (./gradle compileJava), I get a warning:

warning: Supported source version ‘RELEASE_6’ from annotation processor ‘org.eclipse.sisu.space.SisuIndexAPT6’ less than -source ‘1.7’

There is no such dependency directly in my projects.

How can I find out from where is the warning coming from? How can I fix it?

This annotation processor probably leaks in through a transitive dependency. Gradle 5.0 will ignore these automatically. In the meantime you can already opt-in to the new behavior by doing

compileJava.options.annotationProcessorPath = configurations.annotationProcessor