[ONOS-7731] Add a set of interfaces for openstack vTap app

Change-Id: Ic44030a996bb6c3d5883acfdb3ac310a290682f6
diff --git a/apps/openstackvtap/api/src/main/java/org/onosproject/openstackvtap/api/OpenstackVtapId.java b/apps/openstackvtap/api/src/main/java/org/onosproject/openstackvtap/api/OpenstackVtapId.java
new file mode 100644
index 0000000..ce8945d
--- /dev/null
+++ b/apps/openstackvtap/api/src/main/java/org/onosproject/openstackvtap/api/OpenstackVtapId.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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.openstackvtap.api;
+
+import java.util.Objects;
+import java.util.UUID;
+
+/**
+ * Immutable representation of an openstack vTap identifier.
+ */
+public final class OpenstackVtapId {
+
+    /**
+     * Represents either no vTap, or an unspecified vTap.
+     */
+    public static final OpenstackVtapId NONE = new OpenstackVtapId(null);
+
+    private final UUID uuid;
+
+    // Public construction is prohibited
+    private OpenstackVtapId(UUID uuid) {
+        this.uuid = uuid;
+    }
+
+    // Default constructor for serialization
+    private OpenstackVtapId() {
+        this.uuid = null;
+    }
+
+    /**
+     * Returns an unique UUID.
+     *
+     * @return UUID
+     */
+    public UUID uuid() {
+        return uuid;
+    }
+
+    /**
+     * Creates a vTap identifier using the supplied UUID.
+     *
+     * @param uuid vTap UUID
+     * @return vTap identifier
+     */
+    public static OpenstackVtapId vTapId(UUID uuid) {
+        return new OpenstackVtapId(uuid);
+    }
+
+    /**
+     * Creates a vTap identifier using the supplied string format of UUID.
+     *
+     * @param uuidString vTap UUID
+     * @return vTap identifier
+     */
+    public static OpenstackVtapId vTapId(String uuidString) {
+        try {
+            return vTapId(UUID.fromString(uuidString));
+        } catch (Exception e) {
+            throw new IllegalArgumentException("Invalid UUID string: " + uuidString);
+        }
+    }
+
+    /**
+     * Creates a OpenstackVtap id using random uuid.
+     *
+     * @return OpenstackVtap identifier
+     */
+    public static OpenstackVtapId vTapId() {
+        return new OpenstackVtapId(UUID.randomUUID());
+    }
+
+    @Override
+    public String toString() {
+        return uuid.toString();
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(uuid);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj instanceof OpenstackVtapId) {
+            final OpenstackVtapId other = (OpenstackVtapId) obj;
+            return Objects.equals(this.uuid, other.uuid);
+        }
+        return false;
+    }
+}