Implement service for mastership-based remote Java proxies

Change-Id: I36228fcc79b73550fbf5d6cbbc8b24e01d869957
diff --git a/core/api/src/main/java/org/onosproject/mastership/MastershipProxyFactory.java b/core/api/src/main/java/org/onosproject/mastership/MastershipProxyFactory.java
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index 0000000..3bc180c
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+++ b/core/api/src/main/java/org/onosproject/mastership/MastershipProxyFactory.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018-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.mastership;
+
+import org.onosproject.net.DeviceId;
+
+/**
+ * Mastership-based proxy factory.
+ * <p>
+ * The mastership-based proxy factory constructs proxy instances for the master node of a given {@link DeviceId}.
+ * When a proxy method is invoked, the method will be called on the master node for the device.
+ */
+public interface MastershipProxyFactory<T> {
+
+    /**
+     * Returns the proxy for the given device.
+     *
+     * @param deviceId the device identifier
+     * @return the proxy for the given device
+     */
+    T getProxyFor(DeviceId deviceId);
+
+}