[ONOS-4753] Identity/identityref implementation and UT

Change-Id: I40148fa228465555be3bdf410cc294ffc0f34c18
diff --git a/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/translator/tojava/YangDataModelFactory.java b/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/translator/tojava/YangDataModelFactory.java
index 4d68fe2..9ba4068 100644
--- a/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/translator/tojava/YangDataModelFactory.java
+++ b/utils/yangutils/plugin/src/main/java/org/onosproject/yangutils/translator/tojava/YangDataModelFactory.java
@@ -20,6 +20,7 @@
 import org.onosproject.yangutils.datamodel.YangChoice;
 import org.onosproject.yangutils.datamodel.YangContainer;
 import org.onosproject.yangutils.datamodel.YangGrouping;
+import org.onosproject.yangutils.datamodel.YangIdentity;
 import org.onosproject.yangutils.datamodel.YangInput;
 import org.onosproject.yangutils.datamodel.YangLeaf;
 import org.onosproject.yangutils.datamodel.YangLeafList;
@@ -41,6 +42,7 @@
 import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaContainer;
 import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaEnumeration;
 import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaGrouping;
+import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaIdentity;
 import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaInput;
 import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaLeaf;
 import org.onosproject.yangutils.translator.tojava.javamodel.YangJavaLeafList;
@@ -163,6 +165,24 @@
      * generated
      * @return the corresponding inherited node based on the target language
      */
+    public static YangIdentity getYangIdentityNode(GeneratedLanguage targetLanguage) {
+        switch (targetLanguage) {
+            case JAVA_GENERATION: {
+                return new YangJavaIdentity();
+            }
+            default: {
+                throw new TranslatorException("Only YANG to Java is supported.");
+            }
+        }
+    }
+
+    /**
+     * Returns based on the target language generate the inherited data model node.
+     *
+     * @param targetLanguage target language in which YANG mapping needs to be
+     * generated
+     * @return the corresponding inherited node based on the target language
+     */
     public static YangGrouping getYangGroupingNode(GeneratedLanguage targetLanguage) {
         switch (targetLanguage) {
             case JAVA_GENERATION: {