Restructured api to multiple packages

Change-Id: I8a3bb2297ef55fa7749bb312b01a4929d1b360f6
diff --git a/src/main/java/org/opencord/cordvtn/api/net/VtnNetworkEvent.java b/src/main/java/org/opencord/cordvtn/api/net/VtnNetworkEvent.java
new file mode 100644
index 0000000..c6f187f
--- /dev/null
+++ b/src/main/java/org/opencord/cordvtn/api/net/VtnNetworkEvent.java
@@ -0,0 +1,112 @@
+/*
+ * Copyright 2016-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.opencord.cordvtn.api.net;
+
+import org.joda.time.LocalDateTime;
+import org.onosproject.event.AbstractEvent;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+
+/**
+ * Describes vtn network event.
+ */
+public class VtnNetworkEvent extends AbstractEvent<VtnNetworkEvent.Type, VtnNetwork> {
+
+    private final VtnPort vtnPort;
+
+    /**
+     * Type of vtn network event.
+     */
+    public enum Type {
+        /**
+         * Signifies that a new vtn network has been created.
+         */
+        VTN_NETWORK_CREATED,
+
+        /**
+         * Signifies that some vtn network attributes have changed.
+         */
+        VTN_NETWORK_UPDATED,
+
+        /**
+         * Signifies that a vtn network has been removed.
+         */
+        VTN_NETWORK_REMOVED,
+
+        /**
+         * Signifies that a new vtn port has been created.
+         */
+        VTN_PORT_CREATED,
+
+        /**
+         * Signifies that some vtn port attributes have changed.
+         */
+        VTN_PORT_UPDATED,
+
+        /**
+         * Signifies that a vtn port has been removed.
+         */
+        VTN_PORT_REMOVED
+    }
+
+    /**
+     * Creates an event of a given type and for the specified vtn network and
+     * the current time.
+     *
+     * @param type   vtn network event type
+     * @param vtnNet vtn network subject
+     */
+    public VtnNetworkEvent(Type type, VtnNetwork vtnNet) {
+        super(type, vtnNet);
+        this.vtnPort = null;
+    }
+
+    /**
+     * Creates an event of a given type and for the specified vtn network,
+     * port and the current time.
+     *
+     * @param type    vtn network event type
+     * @param vtnNet  vtn network subject
+     * @param vtnPort optional vtn port subject
+     */
+    public VtnNetworkEvent(Type type, VtnNetwork vtnNet, VtnPort vtnPort) {
+        super(type, vtnNet);
+        this.vtnPort = vtnPort;
+    }
+
+    /**
+     * Returns the vtn port subject.
+     * It returns valid value only with the vtn port events.
+     *
+     * @return vtn port or null if the event is not vtn port specific
+     */
+    public VtnPort vtnPort() {
+        return vtnPort;
+    }
+
+    @Override
+    public String toString() {
+        if (vtnPort == null) {
+            return super.toString();
+        }
+        return toStringHelper(this)
+                .add("time", new LocalDateTime(time()))
+                .add("type", type())
+                .add("vtnNet", subject())
+                .add("vtnPort", vtnPort)
+                .toString();
+    }
+}