Mark constructors provided for Serializers, deprecated

Change-Id: Ia9f363d4df811c296ebc24e0624fc0e08bab1aa8
diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java
index 5fd3b82..03c1a43 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/LinkEvent.java
@@ -15,8 +15,9 @@
     protected final SwitchPort dst;
 
     /**
-     * Default constructor.
+     * Default constructor for Serializer to use.
      */
+    @Deprecated
     public LinkEvent() {
 	src = null;
 	dst = null;