Mark constructors provided for Serializers, deprecated

Change-Id: Ia9f363d4df811c296ebc24e0624fc0e08bab1aa8
diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java
index 84b9360..f483e77 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/SwitchEvent.java
@@ -12,8 +12,9 @@
     protected final Long dpid;
 
     /**
-     * Default constructor.
+     * Default constructor for Serializer to use.
      */
+    @Deprecated
     public SwitchEvent() {
 	dpid = null;
     }