Its a method that has been compiled (nmethod, or native method) that is been marked not entrant (enterable) for whatever reason.
That's what I thought. I just can't see the circumstance in which it applies. E.g. above I show paintComponent as the method and I just don't understand how paintComponent would no longer be "enterable" (all of the UI is still visible throughout my test)
Perhaps I just need more coffee... or I'm oversimplifying.
Is it correct to equate non-entrant with respect to methods as an equivalent of 'unreachable' with respect to objects?