@Transition(to = "STANDBY", from = "OFFLINE")
  public void onBecomeStandbyFromOffline(Message message, NotificationContext context) {
    logger.trace("{} Becoming STANDBY from OFFLINE of Partition {}", helixVcrClusterParticipant.getCurrentDataNodeId(),
        message.getPartitionName());
  }
{@link StateModel} to use when the VCR participants register to Helix. The methods are callbacks
that get called within a participant whenever its state changes in Helix.
ambry-cloud/src/main/java/com/github/ambry/cloud/LeaderStandbyHelixVcrStateModel.java