docs: public static Cluster cloneCluster(Cluster cluster) {
          // Could add a better .clone() implementation that clones the derived
          // data structures. The constructor invoked by this clone implementation
          // can be slow for large numbers of partitions. Probably faster to copy
          // all the maps and stuff.
          return new Cluster(cluster.getName(),
                             new ArrayList<Node>(cluster.getNodes()),
                             new ArrayList<Zone>(cluster.getZones()));
          /*-
           * Historic "clone" code being kept in case this, for some reason, was the "right" way to be doing this.
          ClusterMapper mapper = new ClusterMapper();
          return mapper.readCluster(new StringReader(mapper.writeCluster(cluster)));
           */
      }