null provider changes for karaf 4.2.1 CLI

Change-Id: Iee039332a1ff00f7957b58a8bf9c320fba974e15
diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java b/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java
index 9ebcf4b..1be41d6 100644
--- a/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/cli/NullControlCommand.java
@@ -17,9 +17,11 @@
 
 import org.apache.karaf.shell.api.action.Argument;
 import org.apache.karaf.shell.api.action.Command;
+import org.apache.karaf.shell.api.action.Completion;
 import org.apache.karaf.shell.api.action.lifecycle.Service;
 import org.onosproject.cfg.ComponentConfigService;
 import org.onosproject.cli.AbstractShellCommand;
+import org.onosproject.cli.StartStopCompleter;
 import org.onosproject.provider.nil.NullProviders;
 import org.onosproject.provider.nil.TopologySimulator;
 
@@ -35,11 +37,13 @@
 
     @Argument(index = 0, name = "cmd", description = "Control command: start/stop",
             required = true)
+    @Completion(StartStopCompleter.class)
     String cmd = null;
 
     @Argument(index = 1, name = "topoShape",
             description = "Topology shape: e.g. configured, linear, reroute, " +
                     "centipede, tree, spineleaf, mesh, fattree, custom")
+    @Completion(TopologyShapeCompleter.class)
     String topoShape = null;
 
     @Override