Could you give me some hints on how to configure eclipse to be able to debug gradle or a plugin while building?
You could add remote debugging JVM parameters to GRADLE_OPTS:
-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005
In Eclipse you’d then connect to the port you set up like this.
I wonder if the OP was as disappointed with this answer as I?