code: public static String toHexString(byte b) {
      StringBuffer sb = new StringBuffer(4);
      sb.append("0x").append(HEX_CHARS[0x0F & (b >> 4)])
          .append(HEX_CHARS[b & 0x0F]);
      return sb.toString();
    }
docs: Returns the value of {@code b} as a hexadecimal string, starting with "0x".
  
  @param b
  the byte
  @return the string representation of {@code b} in hexadecimal, with a
  leading "0x".