Small fix to not update non-changed state when receiving MQTT message.

eraser-base/src/main/java/de/tudresden/inf/st/eraser/openhab2/mqtt/MQTTUpdater.java

@@ -57,10 +57,13 @@ public class MQTTUpdater implements AutoCloseable {
   }
 
   private void itemUpdate(Item item, String state) {
+    String oldState = item.getStateAsString();
+    if (oldState == null || !oldState.equals(state)) {
       this.logger.debug("Update state of {} [{}] from '{}' to '{}'.",
-        item.getLabel(), item.getID(), item.getStateAsString(), state);
+          item.getLabel(), item.getID(), oldState, state);
       item.setStateFromString(state, false);
     }
+  }
 
   /**
    * Waits until this updater is ready to receive MQTT messages.

eraser-base/src/main/java/de/tudresden/inf/st/eraser/util/MqttReceiver.java

 package de.tudresden.inf.st.eraser.util;
 
-import de.tudresden.inf.st.eraser.openhab2.mqtt.MQTTUpdater;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.fusesource.hawtbuf.Buffer;
@@ -40,7 +39,7 @@ public class MqttReceiver implements AutoCloseable {
   private QoS qos;
 
   public MqttReceiver() {
-    this.logger = LogManager.getLogger(MQTTUpdater.class);
+    this.logger = LogManager.getLogger(MqttReceiver.class);
     this.readyLock = new ReentrantLock();
     this.readyCondition = readyLock.newCondition();
     this.ready = false;