docs: public static int rowKeyContainsMetric(final byte[] metric, 
        final byte[] row_key) {
      int idx = Const.SALT_WIDTH();
      for (int i = 0; i < metric.length; i++, idx++) {
        if (metric[i] != row_key[idx]) {
          return (metric[i] & 0xFF) - (row_key[idx] & 0xFF);  // "promote" to unsigned.
        }
      }
      return 0;
    }