If AsmDecompiler.parseClass is invoked on Java 11 for a class that already uses nest-based access control, parsing with asm (on master) will fail with an UnsupportedOperationException in org.objectweb.asm.ClassVisitor#visitNestMemberExperimental or visitNestHostExperimental.
A trivial fix is to bump org.codehaus.groovy.control.CompilerConfiguration#ASM_API_VERSION to ASM7_EXPERIMENTAL with asm 6.2.
For the 2.5.x-branch, an upgrade from asm 6.1.1 to 6.2 is necessary.
./gradlew test is clean for both branches.
Side note: I've added the maven plugin to allow deployment of the artifacts into the local maven repo. I suspect, it should to removed from the PRs?