[ONOS-4753] Identity/identityref implementation and UT

Change-Id: I40148fa228465555be3bdf410cc294ffc0f34c18
diff --git a/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile1.yang b/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile1.yang
new file mode 100644
index 0000000..fe987ea
--- /dev/null
+++ b/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile1.yang
@@ -0,0 +1,27 @@
+module syslog1 {
+    yang-version 1;
+    namespace "http://huawei3.com";
+    prefix "sys1";
+
+    include "syslog2";
+
+    identity ipv4-address-family {
+       base ref-address-family;
+    }
+
+    identity ipv6-address-family {
+       base ref-address-family;
+    }
+
+    leaf tunnel {
+        type identityref {
+            base ref-address-family;
+        }
+    }
+
+    leaf-list network-ref {
+        type identityref {
+            base ref-address-family;
+        }
+    }
+}
diff --git a/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile2.yang b/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile2.yang
new file mode 100644
index 0000000..14fd83c
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+++ b/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile2.yang
@@ -0,0 +1,19 @@
+submodule syslog2 {
+     yang-version 1;
+     belongs-to "syslog1" {
+         prefix "sys1";
+     }
+
+     import "syslog3" {
+        prefix "sys3";
+     }
+
+     identity tunnel-type {
+         base sys3:final-address-family;
+     }
+
+     identity ref-address-family {
+         base sys3:final-address-family;
+     }
+}
+
diff --git a/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile3.yang b/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile3.yang
new file mode 100644
index 0000000..aa056f0
--- /dev/null
+++ b/utils/yangutils/plugin/src/test/resources/interfileidentityincludedependency/featurefile3.yang
@@ -0,0 +1,10 @@
+module syslog3 {
+     yang-version 1;
+     namespace "http://huawei3.com";
+     prefix "sys3";
+
+     identity final-address-family {
+         description
+            "Base identity from which specific tunnel types are derived.";
+     }
+}