@Override
      public int compare(Map.Entry<ServerName, Integer> o1, Map.Entry<ServerName, Integer> o2) {
        return o1.getValue().compareTo(o2.getValue());
      }
Create the dead server to send. A dead server is sent NB_SEND times. We send at max
MAX_SERVER_PER_MESSAGE at a time. if there are too many dead servers, we send the newly dead
first.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/ClusterStatusPublisher.java