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

Change-Id: I821920fa8c88e64406b702c2b8736bdeaf231474
diff --git a/plugin/src/test/resources/default/DefaultInvalidValueDecimal64InLeaf.yang b/plugin/src/test/resources/default/DefaultInvalidValueDecimal64InLeaf.yang
new file mode 100644
index 0000000..305235f
--- /dev/null
+++ b/plugin/src/test/resources/default/DefaultInvalidValueDecimal64InLeaf.yang
@@ -0,0 +1,13 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+
+    leaf mydecimal {
+        type decimal64 {
+           fraction-digits 4;
+           range 4..6;
+        } 
+        default "x";
+    }
+}