[ONOS-4910, ONOS-4921] Framework: utils validation and defect fix

Change-Id: I821920fa8c88e64406b702c2b8736bdeaf231474
diff --git a/plugin/src/test/resources/default/DefaultInvalidValueBitsInLeaf.yang b/plugin/src/test/resources/default/DefaultInvalidValueBitsInLeaf.yang
new file mode 100644
index 0000000..2e84cf3
--- /dev/null
+++ b/plugin/src/test/resources/default/DefaultInvalidValueBitsInLeaf.yang
@@ -0,0 +1,20 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+
+     leaf mybits {
+         type bits {
+             bit disable-nagle {
+                 position 0;
+             }
+             bit auto-sense-speed {
+                 position 1;
+             }
+             bit Mb-only {
+                 position 2;
+             }
+         }
+         default "xyz";
+     }
+}