[ONOS-7573][Test successful] Mark online does not notify peers device subsystem

Change-Id: Ie347241325047cb65c836c849bec6aebad758820
diff --git a/core/store/dist/src/main/java/org/onosproject/store/device/impl/InternalDeviceStatusChangeEvent.java b/core/store/dist/src/main/java/org/onosproject/store/device/impl/InternalDeviceStatusChangeEvent.java
new file mode 100644
index 0000000..6763615
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onosproject/store/device/impl/InternalDeviceStatusChangeEvent.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2014-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.store.device.impl;
+
+import org.onosproject.net.DeviceId;
+import org.onosproject.store.Timestamp;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Information published by GossipDeviceStore to notify peers of a device
+ * going offline.
+ */
+public class InternalDeviceStatusChangeEvent {
+
+    private final DeviceId deviceId;
+    private final Timestamp timestamp;
+    private final Boolean available;
+
+    /**
+     * Creates a InternalDeviceStatusChangeEvent.
+     * @param deviceId identifier of device.
+     * @param timestamp timestamp of when the device status is changed.
+     * @param available device status is available or not.
+     */
+    public InternalDeviceStatusChangeEvent(DeviceId deviceId, Timestamp timestamp, Boolean available) {
+        this.deviceId = deviceId;
+        this.timestamp = timestamp;
+        this.available = available;
+    }
+
+    public DeviceId deviceId() {
+        return deviceId;
+    }
+
+    public Timestamp timestamp() {
+        return timestamp;
+    }
+
+    public Boolean available() {
+        return available;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("deviceId", deviceId)
+                .add("timestamp", timestamp)
+                .add("available", available)
+                .toString();
+    }
+
+    // for serializer
+    @SuppressWarnings("unused")
+    private InternalDeviceStatusChangeEvent() {
+        deviceId = null;
+        timestamp = null;
+        available = null;
+    }
+}