* try (EchoClient echoClient = EchoClient.create()) {
   *   PagedExpandRequest request = PagedExpandRequest.newBuilder().build();
   *   ApiFuture<PagedExpandPagedResponse> future =
   *       echoClient.pagedExpandPagedCallable().futureCall(request);
   *   // Do something.
   *   for (PagedExpandResponse element : future.get().iterateAll()) {
   *     // doThingsWith(element);
   *   }
   * }

   * try (EchoClient echoClient = EchoClient.create()) {
   *   PagedExpandRequest request = PagedExpandRequest.newBuilder().build();
   *   while (true) {
   *     PagedExpandResponse response = echoClient.pagedExpandCallable().call(request);
   *     for (PagedExpandResponse element : response.getResponsesList()) {
   *       // doThingsWith(element);
   *     }
   *     String nextPageToken = response.getNextPageToken();
   *     if (!String.isNullOrEmpty(nextPageToken)) {
   *       request = request.toBuilder().setPageToken(nextPageToken).build();
   *     } else {
   *       break;
   *     }
   *   }
   * }