Make Logger instance final as SL4J suggests
diff --git a/src/main/java/net/onrc/onos/ofcontroller/core/internal/TopoSwitchServiceImpl.java b/src/main/java/net/onrc/onos/ofcontroller/core/internal/TopoSwitchServiceImpl.java
index cd3cf15..1f39a38 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/core/internal/TopoSwitchServiceImpl.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/core/internal/TopoSwitchServiceImpl.java
@@ -11,7 +11,7 @@
 public class TopoSwitchServiceImpl implements ITopoSwitchService {
 	
 	private GraphDBOperation op;
-	protected static Logger log = LoggerFactory.getLogger(TopoSwitchServiceImpl.class);
+	protected final static Logger log = LoggerFactory.getLogger(TopoSwitchServiceImpl.class);
 
 	public TopoSwitchServiceImpl(String conf) {
 		op = new GraphDBOperation(conf);