code: public int length() {
          int length = 1 + 2 + deviceToken.length + 2 + payload.length;
          final int marshalledLength = marshall().length;
          assert marshalledLength == length;
          return length;
      }
docs: Returns the length of the message in bytes as it is encoded on the wire.
  
  Apple require the message to be of length 255 bytes or less.
  
  @return length of encoded message in bytes