@Override
  public void updateClusterMetrics(ClusterMetrics st) {
    this.clusterStatus = st;
    if (useRegionFinder) {
      regionFinder.setClusterMetrics(st);
    }
  }
This Constructor accepts an instance of MetricsBalancer, which will be used instead of creating
a new one
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java