Add CLI command to view provisioned subscribers

Change-Id: I67a49d7fa569e9f4f28eb8eaea1b34ba2bd5a5fa
diff --git a/app/src/main/java/org/onosproject/olt/cli/ShowSubscribersCommand.java b/app/src/main/java/org/onosproject/olt/cli/ShowSubscribersCommand.java
new file mode 100644
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+++ b/app/src/main/java/org/onosproject/olt/cli/ShowSubscribersCommand.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2016 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.olt.cli;
+
+import org.apache.karaf.shell.commands.Command;
+import org.onlab.packet.VlanId;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.olt.AccessDeviceService;
+
+import java.util.Map;
+
+/**
+ * Shows provisioned subscribers.
+ */
+@Command(scope = "onos", name = "subscribers",
+        description = "Shows provisioned subscribers")
+public class ShowSubscribersCommand extends AbstractShellCommand {
+
+    private static final String FORMAT = "port=%s, cvlan=%s";
+
+    @Override
+    protected void execute() {
+        AccessDeviceService service = AbstractShellCommand.get(AccessDeviceService.class);
+        service.getSubscribers().forEach(this::display);
+    }
+
+    private void display(Map.Entry<ConnectPoint, VlanId> subscriber) {
+        print(FORMAT, subscriber.getKey(), subscriber.getValue());
+    }
+}