config ang key validation and UT for the same

Change-Id: I507740fc9da3f3da5fb3c88a7414f87db6251c5b
diff --git a/utils/yangutils/src/test/resources/ContainerSubStatementList.yang b/utils/yangutils/src/test/resources/ContainerSubStatementList.yang
index 4450391..19810c7 100644
--- a/utils/yangutils/src/test/resources/ContainerSubStatementList.yang
+++ b/utils/yangutils/src/test/resources/ContainerSubStatementList.yang
@@ -4,7 +4,7 @@
     prefix Ant;
     container ospf {
         list valid {
-            key "invalid";
+            key "invalid-interval";
             leaf invalid-interval {
                 type "uint16";
                 units "seconds";