Our use case is during upgrade on a large cluster several NodeManagers may not restart with the new version. Once the RM comes back up the NodeManager will re-register without issue to the RM.
The NM should report the version the RM. The RM should have a configuration to disallow the check (default), equal to the RM (to prevent config change for each release), equal to or greater than RM (to allow NM upgrades), and finally an explicit version or version range.
The RM should also have an configuration on how to treat the mismatch: REJECT, or REBOOT the NM.