[ONOS-3878] YANG Listeners methods for Module and SubModule

Change-Id: Ied2fcf631d302b26ef84af8e98895d8ccb6d6269
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java
new file mode 100644
index 0000000..efb997e
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/parser/impl/listeners/BelongsToListener.java
@@ -0,0 +1,81 @@
+/*
+ * 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.parser.impl.listeners;
+
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/*
+ * Reference: RFC6020 and YANG ANTLR Grammar
+ *
+ * ABNF grammar as per RFC6020
+ * submodule-header-stmts =
+ *                            ;; these stmts can appear in any order
+ *                            [yang-version-stmt stmtsep]
+ *                             belongs-to-stmt stmtsep
+ *
+ * belongs-to-stmt     = belongs-to-keyword sep identifier-arg-str
+ *                       optsep
+ *                       "{" stmtsep
+ *                           prefix-stmt stmtsep
+ *                       "}"
+ *
+ * ANTLR grammar rule
+ * submodule_header_statement : yang_version_stmt? belongs_to_stmt
+ *                            | belongs_to_stmt yang_version_stmt?
+ *                            ;
+ * belongs_to_stmt : BELONGS_TO_KEYWORD IDENTIFIER LEFT_CURLY_BRACE belongs_to_stmt_body RIGHT_CURLY_BRACE;
+ * belongs_to_stmt_body : prefix_stmt;
+ */
+
+/**
+ * Implements listener based call back function corresponding to the "belongs to"
+ * rule defined in ANTLR grammar file for corresponding ABNF rule in RFC 6020.
+ */
+public final class BelongsToListener {
+
+    /**
+     * Creates a new belongto listener.
+     */
+    private BelongsToListener() {
+    }
+
+    /**
+     * It is called when parser receives an input matching the grammar
+     * rule (belongsto), perform validations and update the data model
+     * tree.
+     *
+     * @param listener Listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processBelongsToEntry(TreeWalkListener listener,
+                                             GeneratedYangParser.BelongstoStatementContext ctx) {
+        // TODO method implementation
+    }
+
+    /**
+     * It is called when parser exits from grammar rule (belongsto), it perform
+     * validations and update the data model tree.
+     *
+     * @param listener Listener's object.
+     * @param ctx context object of the grammar rule.
+     */
+    public static void processBelongsToExit(TreeWalkListener listener,
+                                            GeneratedYangParser.BelongstoStatementContext ctx) {
+        // TODO method implementation
+    }
+}