ONOS-5960 Dynamic Config Svc: Datachange Notifications

Change-Id: I46b999530d985b5f9d2bf611f685c1397353997b
diff --git a/apps/config/src/main/java/org/onosproject/config/DynamicConfigEvent.java b/apps/config/src/main/java/org/onosproject/config/DynamicConfigEvent.java
index 8b6a305..9d1b387 100755
--- a/apps/config/src/main/java/org/onosproject/config/DynamicConfigEvent.java
+++ b/apps/config/src/main/java/org/onosproject/config/DynamicConfigEvent.java
@@ -50,7 +50,12 @@
         /**
          * Signifies that dynamic configuration instance was removed.
          */
-        NODE_DELETED
+        NODE_DELETED,
+
+        /**
+         * Signifies an unknown and hence invalid store opeartion.
+         */
+        UNKNOWN_OPRN
     }
 
     /**