Replace Unified* services with MembershipService for subgroup membership

Change-Id: Iabff173ce3501d1ed300513cac445bb712614bd9
diff --git a/core/api/src/main/java/org/onosproject/cluster/Member.java b/core/api/src/main/java/org/onosproject/cluster/Member.java
new file mode 100644
index 0000000..796299b
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/cluster/Member.java
@@ -0,0 +1,83 @@
+/*
+ * 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.cluster;
+
+import java.util.Objects;
+
+import org.onosproject.core.Version;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Controller member identity.
+ */
+public final class Member {
+
+    private final NodeId nodeId;
+    private final Version version;
+
+    /**
+     * Creates a new cluster member identifier from the specified string.
+     *
+     * @param nodeId node identifier
+     * @param version node version
+     */
+    public Member(NodeId nodeId, Version version) {
+        this.nodeId = checkNotNull(nodeId);
+        this.version = version;
+    }
+
+    /**
+     * Returns the node identifier.
+     *
+     * @return the node identifier
+     */
+    public NodeId nodeId() {
+        return nodeId;
+    }
+
+    /**
+     * Returns the node version.
+     *
+     * @return the node version
+     */
+    public Version version() {
+        return version;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(nodeId, version);
+    }
+
+    @Override
+    public boolean equals(Object object) {
+        if (object instanceof Member) {
+            Member member = (Member) object;
+            return member.nodeId.equals(nodeId) && Objects.equals(member.version, version);
+        }
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("nodeId", nodeId)
+                .add("version", version)
+                .toString();
+    }
+}