@Override
  BalanceAction generateCandidate(BalancerClusterState cluster, boolean isWeighing) {
    return generateCandidate(cluster, isWeighing, false);
  }
CandidateGenerator to distribute colocated replicas across different servers.
hbase-balancer/src/main/java/org/apache/hadoop/hbase/master/balancer/DistributeReplicasCandidateGenerator.java