The OperatorCoordinator.resetToCheckpoint() currently lacks the information which checkpoint it recovers to.
That forces implementers to assume strict ordering of method calls between restore and failure. While that is currently guaranteed in this case, it is not guaranteed in other places (see parent issue).
Because of that, we want implementations to not assume method order at all, but rely on explicit information passed to the methods (checkpoint IDs). Otherwise we end up with mixed implementations that partially infer context from the order of method calls, and partially use explicit information that was passed.