CLI command that shows all subnets configured in Segment Routing

Change-Id: Ib03ec2039b763f3796548923883fc89913a1ceac
diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/cli/DeviceSubnetListCommand.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/cli/DeviceSubnetListCommand.java
new file mode 100644
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+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/cli/DeviceSubnetListCommand.java
@@ -0,0 +1,49 @@
+/*
+ * 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.cli;
+
+import org.apache.karaf.shell.commands.Command;
+import org.onlab.packet.Ip4Prefix;
+import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.net.DeviceId;
+import org.onosproject.segmentrouting.SegmentRoutingService;
+
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Command to list device-subnet mapping in Segment Routing.
+ */
+@Command(scope = "onos", name = "sr-device-subnets",
+        description = "List device-subnet mapping in Segment Routing")
+public class DeviceSubnetListCommand extends AbstractShellCommand {
+    @Override
+    protected void execute() {
+        SegmentRoutingService srService =
+                AbstractShellCommand.get(SegmentRoutingService.class);
+        printDeviceSubnetMap(srService.getDeviceSubnetMap());
+    }
+
+    private void printDeviceSubnetMap(Map<DeviceId, Set<Ip4Prefix>> deviceSubnetMap) {
+        deviceSubnetMap.forEach(((deviceId, ip4Prefices) -> {
+            print("%s", deviceId);
+            ip4Prefices.forEach(ip4Prefix -> {
+                print("    %s", ip4Prefix);
+            });
+        }));
+    }
+}