docs: private static byte[] createChecksum(final String hrp, final byte[] values)  {
          byte[] hrpExpanded = expandHrp(hrp);
          byte[] enc = new byte[hrpExpanded.length + values.length + 6];
          System.arraycopy(hrpExpanded, 0, enc, 0, hrpExpanded.length);
          System.arraycopy(values, 0, enc, hrpExpanded.length, values.length);
          int mod = polymod(enc) ^ 1;
          byte[] ret = new byte[6];
          for (int i = 0; i < 6; ++i) {
              ret[i] = (byte) ((mod >>> (5 * (5 - i))) & 31);
          }
          return ret;
      }