I just tried this in Java and I ran quickly into circularity issues (one of the fields has an indirect reference to the same object, say a list which the current instance is part of). How does Lombok cope with that?

It's not that easy as I thought (see my sibling comment).

Even Object.toString could do this using reflection. If you're worried about the performance, override it. I never understood why this is not the case (doesn't Haskell do something similar?).