[ONOS-4351][ONOS-4524] Augment linking and defect fixed.

Change-Id: I7c8e8c90579eea4631e014c4906a543a3c249427
diff --git a/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java b/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java
index e61d273..6787dc9 100644
--- a/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java
+++ b/src/main/java/org/onosproject/yangutils/datamodel/YangCase.java
@@ -92,7 +92,7 @@
  * Represents data model node to maintain information defined in YANG case.
  */
 public class YangCase extends YangNode
-        implements YangLeavesHolder, YangCommonInfo, Parsable, CollisionDetector {
+        implements YangLeavesHolder, YangCommonInfo, Parsable, CollisionDetector, YangAugmentationHolder {
 
     /**
      * Case name.