Consider makingCursorIterator more extensible. It would be reasonable to be able to subclass to provide a range iterator (i.e. a forward iterator that checks an upper bound key, or a reverse iterator checking a lower bound). Since the class is final andtryToComputeNext is private, this is not currently feasible.

Another minor point is that the state machine should probably include aCLOSED state (in whichhasNext returns false, and repeated calls toclose are idempotent).