[ONOS-3892] implement YANG leaf data model

Change-Id: I996d4d3d60a0ad2142e173c6ba26c9cc355ccc80
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java
new file mode 100644
index 0000000..de7355c
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangInclude.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.yangutils.datamodel;
+
+import org.onosproject.yangutils.datamodel.exceptions.DataModelException;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
+
+/*
+ * Reference:RFC 6020.
+ * The "include" statement is used to make content from a submodule
+ *  available to that submodule's parent module, or to another submodule
+ *  of that parent module.  The argument is an identifier that is the
+ *  name of the submodule to include.
+ *  The includes's Substatements
+ *
+ *                +---------------+---------+-------------+------------------+
+ *                | substatement  | section | cardinality |data model mapping|
+ *                +---------------+---------+-------------+------------------+
+ *                | revision-date | 7.1.5.1 | 0..1        | string           |
+ *                +---------------+---------+-------------+------------------+
+ */
+/**
+ * Maintains the information about the included sub-modules.
+ *
+ */
+public class YangInclude implements Parsable {
+
+    /**
+     * Name of the sub-module that is being included.
+     */
+    private String subModuleName;
+
+    /**
+     * The include's "revision-date" statement is used to specify the exact
+     * version of the submodule to import.
+     */
+    private String revision;
+
+    /**
+     * Default constructor.
+     */
+    public YangInclude() {
+    }
+
+    /**
+     * Get the name of included sub-module.
+     *
+     * @return the sub-module name
+     */
+    public String getSubModuleName() {
+        return subModuleName;
+    }
+
+    /**
+     * Set the name of included sub-modules.
+     *
+     * @param subModuleName the sub-module name to set
+     */
+    public void setSubModuleName(String subModuleName) {
+        this.subModuleName = subModuleName;
+    }
+
+    /**
+     * Get the revision.
+     *
+     * @return the revision
+     */
+    public String getRevision() {
+        return revision;
+    }
+
+    /**
+     * Set the revision.
+     *
+     * @param revision the revision to set
+     */
+    public void setRevision(String revision) {
+        this.revision = revision;
+    }
+
+    /**
+     * Returns the type of parsed data.
+     *
+     * @return returns INCLUDE_DATA
+     */
+    public ParsableDataType getParsableDataType() {
+        return ParsableDataType.INCLUDE_DATA;
+    }
+
+    /**
+     * Validate the data on entering the corresponding parse tree node.
+     *
+     * @throws DataModelException a violation of data model rules
+     */
+    public void validateDataOnEntry() throws DataModelException {
+        // TODO auto-generated method stub, to be implemented by parser
+
+    }
+
+    /**
+     * Validate the data on exiting the corresponding parse tree node.
+     *
+     * @throws DataModelException a violation of data model rules
+     */
+    public void validateDataOnExit() throws DataModelException {
+        // TODO auto-generated method stub, to be implemented by parser
+
+    }
+
+}