docs: @Override
    public String getNameFor(Cluster<?> cluster) {
      String nam = names.get(cluster);
      if(nam == null) {
        updateNames();
        nam = names.get(cluster);
      }
      if(nam.endsWith(NULLPOSTFIX)) {
        String basename = nam.substring(0, nam.length() - NULLPOSTFIX.length());
        if(namefreq.getInt(basename) == 1) {
          nam = basename;
        }
      }
      return nam;
    }