@Override
  public String toString() {
    return replicaId.getPartitionId() + ":" + replicaId.getDataNodeId() + ":" + replicaId.getReplicaPath();
  }
get the token to persist. Returns either the candidate token if enough time has passed since it was
set, or the last token again.
ambry-replication/src/main/java/com/github/ambry/replication/RemoteReplicaInfo.java