code: public byte[] marshall() {
          if (marshall == null) {
              marshall = Utilities.marshallEnhanced(COMMAND, identifier,
                      expiry, deviceToken, payload);
          }
          return marshall.clone();
      }
docs: Returns the binary representation of the message as expected by the
  APNS server.
  
  The returned array can be used to sent directly to the APNS server
  (on the wire/socket) without any modification.