Consider a case where my master is getting restarted. RS that was alive when the master restart started, gets restarted before the master initializes the ServerShutDownHandler.
In this case when the RS tries to register with the master, the master will try to expire the server but the server cannot be expired as still the serverShutdownHandler is not enabled.
This case may happen when i have only one RS gets restarted or all the RS gets restarted at the same time.(before assignRootandMeta).
If another RS is brought up then the cluster comes back to normalcy.
May be a very corner case.