Warning with java: it tells you that your solution lacks the cage at the end (or something like that...) by putting it inside [ ] characters. It's a pin in the ass, considering the task to do here, but it works like that. So, no, there are no cages inside other cages. ;)

expected:<...........F...........[[]]> but was:<...........F...........[]>

but, "All cages are intact (not open-ended), and there are no cages inside other cages".

wtf it's erro?