anchor.diff:    /**
      * MqttClient constructor
      */
  -  MqttClient(E mqttConnection, {String clientID: '', num qos: 0x0, bool cleanSession:true} )
  +  MqttClient(E mqttConnection, {String clientID: '', num qos: 0x0, bool cleanSession:true, String this.userName, String this.userPassword} )
                 : _mqttConnection = mqttConnection, _clientID = clientID, _qos = qos, _cleanSession = cleanSession, debugMessage = false, _will = null;  
     
     /**
  
positive.code:    void _openSession() {
       print("Opening session");
       MqttMessageConnect m = new MqttMessageConnect.setOptions(_clientID, _qos, _cleanSession);
       
       // set will
       m.setWill(_will);
  
negative.code:   var onSubscribeData = null;
    var onConnectionLost = null;
    Map<int, Completer>  _messagesToCompleteMap;
  
    String userName;
    String userPassword;
    
    var _liveTimer;
  
  