Make Logger instance final as SL4J suggests
diff --git a/src/main/java/net/floodlightcontroller/devicemanager/internal/Device.java b/src/main/java/net/floodlightcontroller/devicemanager/internal/Device.java
index 645125e..05ebcf3 100755
--- a/src/main/java/net/floodlightcontroller/devicemanager/internal/Device.java
+++ b/src/main/java/net/floodlightcontroller/devicemanager/internal/Device.java
@@ -50,7 +50,7 @@
  */
 @JsonSerialize(using=DeviceSerializer.class)
 public class Device implements IDevice {
-    protected static Logger log =
+    protected final static Logger log =
             LoggerFactory.getLogger(Device.class);
 
     protected Long deviceKey;