code: private static String generateString(byte[] bytes) {
  
      StringBuffer sb = new StringBuffer();
  
      for (byte b : bytes) {
  
        int v = b & 0xFF;
  
        sb.append((char) HEX.charAt(v >> 4));
        sb.append((char) HEX.charAt(v & 0x0f));
      }
  
      return sb.toString();
    }
docs: Converts the array of bytes into a HEX string.
  
  @param bytes
  byte array
  @return HEX string