Trace messages via openflow

Change-Id: If823a75a35501914dc7da265b177cac81d8238ac
diff --git a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
index 974a71c..b704e51 100644
--- a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
+++ b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OpenFlowControllerImpl.java
@@ -313,6 +313,9 @@
     @Override
     public void processPacket(Dpid dpid, OFMessage msg) {
         OpenFlowSwitch sw = this.getSwitch(dpid);
+        if (log.isTraceEnabled()) {
+            log.trace("Processing message from switch {} via openflow: {}", dpid, msg);
+        }
 
         // Check if someone is waiting for this message
         ConcurrentMap<Long, CompletableFuture<OFMessage>> xids = responses.get(dpid);