Refactored pseudowire code.

This refactoring is needed in order to be able to further
refactor the sr application in api / app / web, where api contains
the interfaces, used by other modules, app contains the implementations
and web contains rest related code.

Change-Id: I147442e5d1248941a6c3c4df2715b01e72c40b3f
diff --git a/src/main/java/org/onosproject/segmentrouting/pwaas/L2TunnelDescription.java b/src/main/java/org/onosproject/segmentrouting/pwaas/L2TunnelDescription.java
new file mode 100644
index 0000000..7be187a
--- /dev/null
+++ b/src/main/java/org/onosproject/segmentrouting/pwaas/L2TunnelDescription.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2016-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.segmentrouting.pwaas;
+
+public interface L2TunnelDescription {
+
+    /**
+     * Returns the l2 tunnel.
+     *
+     * @return the l2 tunnel
+     */
+    L2Tunnel l2Tunnel();
+
+    /**
+     * Returns the l2 tunnel policy.
+     *
+     * @return the l2 tunnel policy.
+     */
+    L2TunnelPolicy l2TunnelPolicy();
+
+    /**
+     * Sets the l2 tunnel.
+     *
+     * @param tunnel the l2 tunnel to set.
+     */
+    void setL2Tunnel(L2Tunnel tunnel);
+
+    /**
+     * Sets the l2 policy.
+     *
+     * @param policy the policy to set.
+     */
+    void setL2TunnelPolicy(L2TunnelPolicy policy);
+}