- make logger final

- simplify mqtt topic

workspace/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ttn/TtnListener.java

@@ -15,9 +15,11 @@ import org.slf4j.LoggerFactory;
  */
 public final class TtnListener {
     
-    private static Logger LOG = LoggerFactory.getLogger(TtnListener.class);
+    private static final Logger LOG = LoggerFactory.getLogger(TtnListener.class);
     private static final long DISCONNECT_TIMEOUT_MS = 3000;
     
+    private static final String TOPIC = "+/devices/+/up";
+    
     private final String clientId;
     private final IMessageReceived callback;
     private final String url;
@@ -41,7 +43,7 @@ public final class TtnListener {
         this.clientId = UUID.randomUUID().toString();
         this.appId = appId;
         this.appKey = appKey;
-        this.topic = appId + "/devices/+/up";
+        this.topic = TOPIC;
     }
     
     /**