@Override
    public void getReplicaIdsByStates(Map<ReplicaState, List<AmbryReplica>> replicasByState, AmbryPartition partition,
        Set<ReplicaState> states, String dcName) {
      for (ReplicaState state : states) {
        List<AmbryReplica> replicas = getReplicaIdsByState(partition, state, dcName);
        replicasByState.put(state, replicas);
      }
    }
{@inheritDoc}
If dcName is null, then get replicas by given state from all datacenters.
If no routing table snapshot is found for dc name, or no resource name found for given partition, return empty list.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HelixClusterManager.java