code: public byte[] submitSmResp(int sequenceNumber, String messageId)
              throws PDUStringException {
          StringValidator.validateString(messageId, StringParameter.MESSAGE_ID);
  
          PDUByteBuffer buf = new PDUByteBuffer(SMPPConstant.CID_SUBMIT_SM_RESP,
                  0, sequenceNumber);
          buf.append(messageId);
          return buf.toBytes();
      }
docs: /*
  (non-Javadoc)
  
  @see org.jsmpp.util.PDUComposer#submitSmResp(int, java.lang.String)