Mesos does not validate framework-supplied FrameworkIDs

Since Mesos masters do not persist frameworks (MESOS-1719) we might subscribe schedulers with self-assigned FrameworkIDs.

While we cannot confirm that used FrameworkIDs were indeed assigned by Mesos masters, we should still validate the supplied values to make sure they do not break our internal assumptions (e.g., IDs might be used to construct filesystem paths).