[ONOS-4352]Defect fix for unsupported types.

Change-Id: I5c1425518422492de8e108c54ea82f0c85812157
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java
index 91bc61a..03c4983 100644
--- a/utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/utils/YangConstructType.java
@@ -350,6 +350,21 @@
     REFINE_DATA,
 
     /**
+     * Identifies the YANG leafref element parsed data.
+     */
+    LEAFREF_DATA,
+
+    /**
+     * Identifies the YANG identityref element parsed data.
+     */
+    IDENTITYREF_DATA,
+
+    /**
+     * Identifies the YANG instance identifier element parsed data.
+     */
+    INSTANCE_IDENTIFIER_DATA,
+
+    /**
      * Identifies the YANG deviation element parsed data.
      */
     DEVIATION_DATA,
@@ -500,6 +515,12 @@
                 return "unique";
             case REFINE_DATA:
                 return "refine";
+            case LEAFREF_DATA:
+                return "leafref";
+            case IDENTITYREF_DATA:
+                return "identityref";
+            case INSTANCE_IDENTIFIER_DATA:
+                return "instance-identifier";
             case DEVIATION_DATA:
                 return "deviation";
             case ANYXML_DATA: