Support JSON output in external router CLI, make router obj immutable

Change-Id: I6c76d9aafd64c1af7c3e28b42beabc268f824b88
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/IpAddressCompleter.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/IpAddressCompleter.java
index 4ae1dd4..bac877d 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/IpAddressCompleter.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/cli/IpAddressCompleter.java
@@ -38,7 +38,7 @@
         StringsCompleter delegate = new StringsCompleter();
         OpenstackNetworkService osNetService = AbstractShellCommand.get(OpenstackNetworkService.class);
         Set<IpAddress> set = osNetService.externalPeerRouters().stream()
-                .map(ExternalPeerRouter::externalPeerRouterIp)
+                .map(ExternalPeerRouter::ipAddress)
                 .collect(Collectors.toSet());
         SortedSet<String> strings = delegate.getStrings();