code: public ClusterData createClusterData(boolean localOnly) {
      if (localOnly) return new VertxClusterData(vertx);
      HazelcastInstance hazelcast = ClusterListenerFactory.getHazelcastInstance(vertx);
      if (hazelcast != null) {
        return new HazelcastClusterData(hazelcast);
      } else {
        return new VertxClusterData(vertx);
      }
    }
docs: Creates cluster data.
  
  @param localOnly Indicates whether to force the cluster to be local only.
  @return A cluster data store.