Add missing case for ONOS extension
diff --git a/src/main/java/net/floodlightcontroller/linkdiscovery/ILinkDiscovery.java b/src/main/java/net/floodlightcontroller/linkdiscovery/ILinkDiscovery.java
index 31b8923..e65513b 100644
--- a/src/main/java/net/floodlightcontroller/linkdiscovery/ILinkDiscovery.java
+++ b/src/main/java/net/floodlightcontroller/linkdiscovery/ILinkDiscovery.java
@@ -107,6 +107,7 @@
         @Override
         public String toString() {
             switch (operation) {
+            case LINK_ADDED:
             case LINK_REMOVED:
             case LINK_UPDATED:
                 return "LDUpdate [operation=" + operation +