@Override
 public Iterable<? extends Client> execute(
     ListeningExecutorService executor, Predicate<String> clientNameSelector) {
   return execute(executor, filter(api.listClients(), clientNameSelector));
 }
 @Override
 public Iterable<? extends Client> execute(ListeningExecutorService executor) {
   return execute(executor, api.listClients());
 }