Mark constructors provided for Serializers, deprecated

Change-Id: Ia9f363d4df811c296ebc24e0624fc0e08bab1aa8
diff --git a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/DeviceEvent.java b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/DeviceEvent.java
index 628b9d4..8bea7f8 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/networkgraph/DeviceEvent.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/networkgraph/DeviceEvent.java
@@ -30,8 +30,9 @@
 
 
     /**
-     * Default constructor.
+     * Default constructor for Serializer to use.
      */
+    @Deprecated
     public DeviceEvent() {
 	mac = null;
     }