Fix: resolve CLI auto-completion issue of openstack apps

Change-Id: I0dc973628910cae3588f25e066e81a87a4264f06
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/PurgeInstancePortsCommand.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/PurgeInstancePortsCommand.java
index 6109a77..89f6a04 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/PurgeInstancePortsCommand.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/PurgeInstancePortsCommand.java
@@ -17,6 +17,7 @@
 
 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.Option;
 import org.apache.karaf.shell.api.action.lifecycle.Service;
 import org.onosproject.cli.AbstractShellCommand;
@@ -50,6 +51,7 @@
 
     @Argument(index = 0, name = "portIds", description = "Instance Port IDs",
             required = false, multiValued = true)
+    @Completion(InstancePortIdCompleter.class)
     private String[] portIds = null;
 
     @Override