Do you think it is worth more testing towards the iterator?  I recognize that (at least best I can tell) this iterator is simpler than openJDK because the data in the iterator is immutable (where openJDK attempts to have updates may be seen by the iterator).

But the it.remove() function modifies the map, do you think it would be worth trying removals in different situations and verifying the map more afterwards?

If you don't think it is worth it, that's fine, just thought I would ask.