@Override
  synchronized public VcrClusterParticipant getVcrClusterParticipant() throws Exception {
    if (vcrClusterParticipant == null) {
      vcrClusterParticipant =
          new HelixVcrClusterParticipant(cloudConfig, clusterMapConfig, storeConfig, clusterMap, accountService, cloudDestination,
              vcrMetrics);
    }
    return vcrClusterParticipant;
  }
Constructor for {@link HelixVcrClusterAgentsFactory}
@param cloudConfig {@link CloudConfig} object.
@param clusterMapConfig {@link ClusterMapConfig} object.
@param clusterMap {@link ClusterMap} object.
@param accountService {@link AccountService} object.
@param storeConfig {@link StoreConfig} object.
@param cloudDestination {@link CloudDestination} object.
@param metricRegistry  {@link MetricRegistry} object.
ambry-cloud/src/main/java/com/github/ambry/cloud/HelixVcrClusterAgentsFactory.java