code: public static Cluster createCluster(String clusterName,
        CassandraHostConfigurator cassandraHostConfigurator,
        Map<String, String> credentials) {
      synchronized (clusters) {
        Cluster cluster = clusters.get(clusterName);
        if ( cluster == null ) {
          cluster = new ThriftCluster(clusterName,
            cassandraHostConfigurator, credentials);
          clusters.put(clusterName, cluster);
          cluster.onStartup();
        }
        return cluster;
      }
    }
docs: Method looks in the cache for the cluster by name. If none exists, a new
  ThriftCluster instance is created and added to the map of known clusters
  
  @param clusterName
  The cluster name. This is an identifying string for the cluster,
  e.g. "production" or "test" etc. Clusters will be created on
  demand per each unique clusterName key.
  @param cassandraHostConfigurator
  @param credentials