[ONOS-5400][ONOS-5614] identity ref support in yangtools and defect fixes.

Change-Id: Ia1f32a6772e9d468717340953cf7598c61d9f1ed
diff --git a/plugin/maven/src/test/resources/ValidPatternStatement.yang b/plugin/maven/src/test/resources/ValidPatternStatement.yang
index 556db31..0c93e9d 100644
--- a/plugin/maven/src/test/resources/ValidPatternStatement.yang
+++ b/plugin/maven/src/test/resources/ValidPatternStatement.yang
@@ -7,4 +7,24 @@
             pattern "[a-zA-Z]";
          }
     }
+    leaf ipv4-address {
+         type string {
+           pattern
+          '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(%[\p{N}\p{L}]+)?';
+         }
+      description
+        "The ipv4-address type represents an IPv4 address in
+       dotted-quad notation.  The IPv4 address may include a zone
+       index, separated by a % sign.
+
+       The zone index is used to disambiguate identical address
+       values.  For link-local addresses, the zone index will
+       typically be the interface index number or the name of an
+       interface.  If the zone index is not present, the default
+       zone of the device will be used.
+
+       The canonical format for the zone index is the numerical
+       format";
+    }
+
 }