CORD-61 Dynamic XConnect support

- Add new XConnectConfig with unit test
- Gather XConnect features into XConnectHandler
- Introduce ObjectiveError.Type.GROUPREMOVALFAILED
- Rename
    - NetworkConfigEventHandler -> AppConfigHandler
    - XConnectNextObjectiveStoreKey -> XConnectStoreKey
    - Test json file
- Refactor

Change-Id: I8ca3176ed976c71ce9e28b7f3722ce80d49c816f
diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/storekey/XConnectStoreKey.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/storekey/XConnectStoreKey.java
new file mode 100644
index 0000000..3849624
--- /dev/null
+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/storekey/XConnectStoreKey.java
@@ -0,0 +1,84 @@
+/*
+ * 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.onosproject.segmentrouting.storekey;
+
+import org.onlab.packet.VlanId;
+import org.onosproject.net.DeviceId;
+
+import java.util.Objects;
+
+/**
+ * Key of VLAN cross-connect next objective store.
+ */
+public class XConnectStoreKey {
+    private final DeviceId deviceId;
+    private final VlanId vlanId;
+
+    /**
+     * Constructs the key of cross-connect next objective store.
+     *
+     * @param deviceId device ID of the VLAN cross-connection
+     * @param vlanId VLAN ID of the VLAN cross-connection
+     */
+    public XConnectStoreKey(DeviceId deviceId, VlanId vlanId) {
+        this.deviceId = deviceId;
+        this.vlanId = vlanId;
+    }
+
+    /**
+     * Returns the device ID of this key.
+     *
+     * @return device ID
+     */
+    public DeviceId deviceId() {
+        return this.deviceId;
+    }
+
+    /**
+     * Returns the VLAN ID of this key.
+     *
+     * @return VLAN ID
+     */
+    public VlanId vlanId() {
+        return this.vlanId;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (!(o instanceof XConnectStoreKey)) {
+            return false;
+        }
+        XConnectStoreKey that =
+                (XConnectStoreKey) o;
+        return (Objects.equals(this.deviceId, that.deviceId) &&
+                Objects.equals(this.vlanId, that.vlanId));
+    }
+
+    // The list of neighbor ids and label are used for comparison.
+    @Override
+    public int hashCode() {
+         return Objects.hash(deviceId, vlanId);
+    }
+
+    @Override
+    public String toString() {
+        return "Device: " + deviceId + " VlanId: " + vlanId;
+    }
+}