[ONOS-4636]YANG Grouping linking bug fix + YANG Code review comment fix

Change-Id: I68ee8dd08266a02593e217cef1a9bb010037d673
(cherry picked from commit 2ee9e7e892456543e0e5532f7b0de3774d42e561)
diff --git a/utils/yangutils/src/test/resources/file1UsesFile2TypeDefFile3Type/ietf-network-topology.yang b/utils/yangutils/src/test/resources/file1UsesFile2TypeDefFile3Type/ietf-network-topology.yang
new file mode 100644
index 0000000..4f426e4
--- /dev/null
+++ b/utils/yangutils/src/test/resources/file1UsesFile2TypeDefFile3Type/ietf-network-topology.yang
@@ -0,0 +1,34 @@
+ module ietf-network-topology {
+   yang-version 1;
+   namespace "urn:ietf:params:xml:ns:yang:ietf-network-topology";
+   prefix lnk;
+
+   import ietf-inet-types {
+     prefix inet;
+   }
+   
+   typedef tp-id {
+     type inet:uri;
+     description
+       "An identifier for termination points on a node.
+        The identifier SHOULD be chosen such that the same TP in a
+        real network topology will always be identified through the
+        same identifier, even if the model is instantiated in
+        separate datastores. An implementation MAY choose to capture
+        semantics in the identifier, for example to indicate the type
+        of TP and/or the type of node and topology that the TP is a
+        part of.";
+   }
+
+   grouping tp-ref {
+     description
+       "References a termination point in a specific node.";
+     leaf tp-ref {
+       type tp-id;
+       description
+         "A type for an absolute reference to a termination point.
+          (This type should not be used for relative references.
+          In such a case, a relative path should be used instead.)";
+     }
+   }
+ }