docs: public Observable<Page<ExpressRouteGatewayInner>> listAsync() {
          return listWithServiceResponseAsync().map(new Func1<ServiceResponse<List<ExpressRouteGatewayInner>>, Page<ExpressRouteGatewayInner>>() {
              @Override
              public Page<ExpressRouteGatewayInner> call(ServiceResponse<List<ExpressRouteGatewayInner>> response) {
                  PageImpl1<ExpressRouteGatewayInner> page = new PageImpl1<>();
                  page.setItems(response.body());
                  return page;
              }
          });
      }