[ONOS-3894, 4071] YANG Advanced Construct Union & Grouping

Change-Id: I0f828adb5884c2d7b6e4120f9843c416608ae5e7
diff --git a/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java b/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
index 07dc946..06dd0d5 100644
--- a/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
+++ b/src/main/java/org/onosproject/yangutils/parser/impl/listeners/ContainerListener.java
@@ -16,6 +16,7 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangCase;
 import org.onosproject.yangutils.datamodel.YangContainer;
 import org.onosproject.yangutils.datamodel.YangList;
 import org.onosproject.yangutils.datamodel.YangModule;
@@ -126,7 +127,7 @@
 
         Parsable curData = listener.getParsedDataStack().peek();
         if (curData instanceof YangModule || curData instanceof YangContainer
-                || curData instanceof YangList) {
+                || curData instanceof YangList || curData instanceof YangCase) {
             YangNode curNode = (YangNode) curData;
             try {
                 curNode.addChild(container);