protected final boolean idleRegionServerExist(BalancerClusterState c) {
    boolean isServerExistsWithMoreRegions = false;
    boolean isServerExistsWithZeroRegions = false;
    for (int[] serverList : c.regionsPerServer) {
      if (serverList.length > 1) {
        isServerExistsWithMoreRegions = true;
      }
      if (serverList.length == 0) {
        isServerExistsWithZeroRegions = true;
      }
    }
    return isServerExistsWithMoreRegions && isServerExistsWithZeroRegions;
  }
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