code: private Page<AvailablePhoneNumberCountry> pageForRequest(final TwilioRestClient client, final Request request) {
          Response response = client.request(request);
  
          if (response == null) {
              throw new ApiConnectionException("AvailablePhoneNumberCountry read failed: Unable to connect to server");
          } else if (!TwilioRestClient.SUCCESS.apply(response.getStatusCode())) {
              RestException restException = RestException.fromJson(response.getStream(), client.getObjectMapper());
              if (restException == null) {
                  throw new ApiException("Server Error, no content");
              }
  
              throw new ApiException(
                  restException.getMessage(),
                  restException.getCode(),
                  restException.getMoreInfo(),
                  restException.getStatus(),
                  null
              );
          }
  
          return Page.fromJson(
              "countries",
              response.getContent(),
              AvailablePhoneNumberCountry.class,
              client.getObjectMapper()
          );
      }
docs: Generate a Page of AvailablePhoneNumberCountry Resources for a given request.
  
  @param client TwilioRestClient with which to make the request
  @param request Request to generate a page for
  @return Page for the Request