private boolean remoteReplicasLeft() {
    for(String dcName : remoteDatacenters) {
      if(!replicaPoolByDc.get(dcName).isEmpty()) {
        return true;
      }
    }
    return false;
  }
Returns true if there are still remote replicas that have not yet been added to the final list (i.e. remoteReplicas),
false otherwise.
ambry-router/src/main/java/com/github/ambry/router/ParanoidDurabilityOperationTracker.java