This method increments a counter to count partition lost events.
After an ungraceful shutdown, backups can have expired entries.
And these entries can remain forever on them. Reason for this is,
the lost invalidations on a primary partition. During ungraceful
shutdown, these invalidations can be lost before sending them to
Here, the counter in this method, is used to detect the lost
invalidations case. If it is detected, we send expiry operations to
remove leftover backup entries. Otherwise leftover entries can remain on
public final void sendQueuedExpiredKeys(T container)