VisitableURLClassLoader does not override any methods related to class loading and does not hold any state, it should be registered as parallel capable.
I see a lot of locking in
VisitableURLClassLoader.loadClass in one of my tasks (that compiles a set of Groovy classes).
See https://blogs.oracle.com/dholmes/entry/parallel_classloading_revisited_fully_concurrent, https://docs.oracle.com/javase/7/docs/api/java/lang/ClassLoader.html.
Is this the wrong place for this suggestion? Should I rather post this in Help/Discuss?