First real test using MQTT to send and receive messages.

- also try to setup CI (might fail)

src/main/resources/MqttUpdater.jadd

@@ -145,6 +145,7 @@ public class MqttUpdater {
 
     // subscribe at broker
     org.fusesource.mqtt.client.Topic[] topicArray = { new org.fusesource.mqtt.client.Topic(topic, this.qos) };
+    connection.getDispatchQueue().execute(() -> {
       connection.subscribe(topicArray, new org.fusesource.mqtt.client.Callback<byte[]>() {
         @Override
         public void onSuccess(byte[] qoses) {
@@ -156,6 +157,7 @@ public class MqttUpdater {
           logger.error("Could not subscribe to {}", topic, cause);
         }
       });
+    });
   }
 
   /**
@@ -187,6 +189,7 @@ public class MqttUpdater {
       logger.warn("Stopping without connection. Was setHost() called?");
       return;
     }
+    connection.getDispatchQueue().execute(() -> {
       connection.disconnect(new org.fusesource.mqtt.client.Callback<Void>() {
         @Override
         public void onSuccess(Void value) {
@@ -198,9 +201,11 @@ public class MqttUpdater {
           // Disconnects never fail. And we do not care either.
         }
       });
+    });
   }
 
   public void publish(String topic, byte[] bytes) {
+    connection.getDispatchQueue().execute(() -> {
       connection.publish(topic, bytes, qos, false, new org.fusesource.mqtt.client.Callback<Void>() {
         @Override
         public void onSuccess(Void value) {
@@ -212,5 +217,6 @@ public class MqttUpdater {
           logger.warn("Could not publish on topic '{}'", topic);
         }
       });
+    });
   }
 }