Make Logger instance final as SL4J suggests
diff --git a/src/main/java/net/floodlightcontroller/core/internal/Controller.java b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
index 134a3b0..17f1be8 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/Controller.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
@@ -152,7 +152,7 @@
 public class Controller implements IFloodlightProviderService, 
             IStorageSourceListener {
     
-    protected static Logger log = LoggerFactory.getLogger(Controller.class);
+    protected final static Logger log = LoggerFactory.getLogger(Controller.class);
 
     private static final String ERROR_DATABASE = 
             "The controller could not communicate with the system database.";
diff --git a/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java b/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java
index 467c74a..5810967 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java
@@ -79,7 +79,7 @@
 public class OFSwitchImpl implements IOFSwitch, IOnosRemoteSwitch {
     // TODO: should we really do logging in the class or should we throw
     // exception that can then be handled by callers?
-    protected static Logger log = LoggerFactory.getLogger(OFSwitchImpl.class);
+    protected final static Logger log = LoggerFactory.getLogger(OFSwitchImpl.class);
 
     private static final String HA_CHECK_SWITCH = 
             "Check the health of the indicated switch.  If the problem " +
diff --git a/src/main/java/net/floodlightcontroller/core/internal/RoleChanger.java b/src/main/java/net/floodlightcontroller/core/internal/RoleChanger.java
index 4924fbc..194935c 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/RoleChanger.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/RoleChanger.java
@@ -120,7 +120,7 @@
     protected Thread workerThread;
     protected long timeout;
     protected static long DEFAULT_TIMEOUT = 15L*1000*1000*1000L; // 15s
-    protected static Logger log = LoggerFactory.getLogger(RoleChanger.class);
+    protected final static Logger log = LoggerFactory.getLogger(RoleChanger.class);
     /** 
      * A queued task to be handled by the Role changer thread. 
      */