[ONOS-3905, ONOS-3901, ONOS-3900] choice, grouping and augment data model support.
Change-Id: Iaee5175e4e06249f5b56192f4744e9297289194c
diff --git a/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java
new file mode 100644
index 0000000..92a1da3
--- /dev/null
+++ b/utils/yangutils/src/main/java/org/onosproject/yangutils/datamodel/YangMust.java
@@ -0,0 +1,152 @@
+/*
+ * 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;
+
+/*-
+ * The "must" statement, which is optional, takes as an argument a string that
+ * contains an XPath expression. It is used to formally declare a constraint
+ * on valid data.
+ *
+ * When a datastore is validated, all "must" constraints are conceptually
+ * evaluated once for each data node in the data tree, and for all leafs with
+ * default values in use. If a data node does not exist in the data tree, and
+ * it does not have a default value, its "must" statements are not evaluated.
+ *
+ * All such constraints MUST evaluate to true for the data to be valid.
+ *
+ * The must's sub-statements
+ *
+ * +---------------+---------+-------------+------------------+
+ * | substatement | section | cardinality |data model mapping|
+ * +---------------+---------+-------------+------------------+
+ * | description | 7.19.3 | 0..1 | -string |
+ * | error-app-tag | 7.5.4.2 | 0..1 | -not supported |
+ * | error-message | 7.5.4.1 | 0..1 | -not supported |
+ * | reference | 7.19.4 | 0..1 | -string |
+ * +---------------+---------+-------------+------------------+
+ */
+
+/**
+ * Maintain information defined in YANG must.
+ */
+public class YangMust implements YangDesc, YangReference, Parsable {
+
+ /**
+ * Constraint info.
+ */
+ private String constratint;
+
+ /**
+ * Description string.
+ */
+ private String description;
+
+ /**
+ * reference string.
+ */
+ private String reference;
+
+ /**
+ * Create a YANG must restriction.
+ */
+ public YangMust() {
+ }
+
+ /**
+ * Get the constraint.
+ *
+ * @return the constraint.
+ */
+ public String getConstratint() {
+ return constratint;
+ }
+
+ /**
+ * Set the constraint.
+ *
+ * @param constratint the constraint to set
+ */
+ public void setConstratint(String constratint) {
+ this.constratint = constratint;
+ }
+
+ /**
+ * Get the description.
+ *
+ * @return the description.
+ */
+ public String getDescription() {
+ return description;
+ }
+
+ /**
+ * Set the description.
+ *
+ * @param description set the description.
+ */
+ public void setDescription(String description) {
+ this.description = description;
+ }
+
+ /**
+ * Get the textual reference.
+ *
+ * @return the reference.
+ */
+ public String getReference() {
+ return reference;
+ }
+
+ /**
+ * Set the textual reference.
+ *
+ * @param reference the reference to set.
+ */
+ public void setReference(String reference) {
+ this.reference = reference;
+ }
+
+ /**
+ * Returns the type of the parsed data.
+ *
+ * @return returns MUST_DATA
+ */
+ public ParsableDataType getParsableDataType() {
+ return ParsableDataType.MUST_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
+ }
+}