Device config synchronizer

- initial sketch of Device Config Synchronizer outline (ONOS-6745)

Change-Id: I57c8ab6c3511f12c15e3501aa61498eb18264b27
diff --git a/apps/configsync/src/main/java/org/onosproject/d/config/sync/DeviceConfigSynchronizationProviderService.java b/apps/configsync/src/main/java/org/onosproject/d/config/sync/DeviceConfigSynchronizationProviderService.java
new file mode 100644
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+++ b/apps/configsync/src/main/java/org/onosproject/d/config/sync/DeviceConfigSynchronizationProviderService.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2017-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.d.config.sync;
+
+import org.onosproject.net.provider.ProviderService;
+
+import com.google.common.annotations.Beta;
+
+/**
+ * Service which configuration synchronization provider can interact
+ * with the service.
+ * <p>
+ * Provides a mean to propagate device triggered change event upward to
+ * dynamic config subsystem.
+ */
+@Beta
+public interface DeviceConfigSynchronizationProviderService
+    extends ProviderService<DeviceConfigSynchronizationProvider> {
+
+    // TODO API to propagate device detected change upwards
+    // e.g., in reaction to NETCONF async notification,
+    //       report polling result up to DynConfig subsystem
+}