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

Change-Id: I68ee8dd08266a02593e217cef1a9bb010037d673
diff --git a/src/test/resources/interfileietf/ietf-schedule.yang b/src/test/resources/interfileietf/ietf-schedule.yang
new file mode 100644
index 0000000..b9f7297
--- /dev/null
+++ b/src/test/resources/interfileietf/ietf-schedule.yang
@@ -0,0 +1,64 @@
+   module ietf-schedule {
+     yang-version 1;
+     namespace "urn:ietf:params:xml:ns:yang:ietf-schedule";
+     // replace with IANA namespace when assigned
+
+     prefix "sch";
+
+     import ietf-yang-types {
+       prefix "yang";
+     }
+
+     organization "TBD";
+     contact "TBD";
+     description
+       "The model allows time scheduling parameters to be specified.";
+
+     revision "2016-03-01" {
+       description "Initial revision";
+       reference "TBD";
+     }
+
+     /*
+      * Groupings
+      */
+
+     grouping schedules {
+       description
+         "A list of schedules defining when a particular
+          configuration takes effect.";
+       container schedules {
+         description
+           "Container of a schedule list defining when a particular
+            configuration takes effect.";
+         list schedule {
+           key "schedule-id";
+           description "A list of schedule elements.";
+
+           leaf schedule-id {
+             type uint32;
+             description "Identifies the schedule element.";
+           }
+           leaf start {
+             type yang:date-and-time;
+             description "Start time.";
+           }
+           leaf schedule-duration {
+             type string {
+               pattern
+                 'P(\d+Y)?(\d+M)?(\d+W)?(\d+D)?T(\d+H)?(\d+M)?(\d+S)?';
+             }
+             description "Schedule duration in ISO 8601 format.";
+           }
+           leaf repeat-interval {
+             type string {
+               pattern
+                 'R\d*/P(\d+Y)?(\d+M)?(\d+W)?(\d+D)?T(\d+H)?(\d+M)?'
+                 + '(\d+S)?';
+             }
+             description "Repeat interval in ISO 8601 format.";
+           }
+         }
+       }
+     } // schedules
+   }