@Override
  public void onInstanceConfigChange(List<InstanceConfig> instanceConfigs, NotificationContext context) {
    for (InstanceConfigChangeListener registeredInstanceConfigChangeListener : registeredInstanceConfigChangeListeners) {
      registeredInstanceConfigChangeListener.onInstanceConfigChange(instanceConfigs, context);
    }
  }
Constructor for {@link HelixVcrClusterSpectator}.
@param cloudConfig Cluster config of vcr.
@param clusterMapConfig Cluster Map config.
ambry-cloud/src/main/java/com/github/ambry/cloud/HelixVcrClusterSpectator.java