The javassist based bytecode enhancer is opt-in, and yet even when choosing the bytebuddy based one Javassist needs to be on the classpath as it's being used for other things as well, such as classpath scanning.

We should be able to implement an alternative for such other uses, so to make javassist truly optional (for now) and removed later.

If that's not possible, work on a plan to fully remove it in 6.