ONOS-5450 Initial implementation of OFAgent

- Refactored OFAgent immutable
- Added OFAgentStore and OFAgentEvent
- Implemented OFAgentManager and OFSwitchManager
- Added unit tests

Change-Id: Ie39ad2db9e6bd6259a062371b3ffe116b8c8cc52
diff --git a/apps/ofagent/src/main/java/org/onosproject/ofagent/api/OFAgentListener.java b/apps/ofagent/src/main/java/org/onosproject/ofagent/api/OFAgentListener.java
new file mode 100644
index 0000000..9cc7982
--- /dev/null
+++ b/apps/ofagent/src/main/java/org/onosproject/ofagent/api/OFAgentListener.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2017-present 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.ofagent.api;
+
+import org.onosproject.event.EventListener;
+
+/**
+ * Listener for OFAgent events.
+ */
+public interface OFAgentListener extends EventListener<OFAgentEvent> {
+}