docs: public static byte[] stringToHash(String s) {
          if (s.length() % 2 != 0) {
              throw new IllegalArgumentException("Invalid hash string: " + s);
          }
          byte[] hash = new byte[s.length() / 2];
          for (int i = 0; i < s.length(); i += 2) {
              byte b = (byte) ((hexDigitValue(s.charAt(i)) << 4) + hexDigitValue(s.charAt(i + 1)));
              hash[i / 2] = b;
          }
          return hash;
      }