@Override
  protected void applyUndelete(MessageInfo remoteBlob, RemoteReplicaInfo remoteReplicaInfo) {
    throw new UnsupportedOperationException("applyUndelete is unsupported");
  }
This method checks if an un-deleted blob from remote on-prem server has been un-deleted from local-store
@param remoteBlob the {@link MessageInfo} that will be transformed into an un-delete
@param remoteReplicaInfo The remote replica that is being replicated from
ambry-replication/src/main/java/com/github/ambry/replication/BackupCheckerThread.java