code: public Observable<ServiceResponse<Page<AppServiceCertificateResourceInner>>> listCertificatesWithServiceResponseAsync(final String resourceGroupName, final String certificateOrderName) {
          return listCertificatesSinglePageAsync(resourceGroupName, certificateOrderName)
              .concatMap(new Func1<ServiceResponse<Page<AppServiceCertificateResourceInner>>, Observable<ServiceResponse<Page<AppServiceCertificateResourceInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<AppServiceCertificateResourceInner>>> call(ServiceResponse<Page<AppServiceCertificateResourceInner>> page) {
                      String nextPageLink = page.body().nextPageLink();
                      if (nextPageLink == null) {
                          return Observable.just(page);
                      }
                      return Observable.just(page).concatWith(listCertificatesNextWithServiceResponseAsync(nextPageLink));
                  }
              });
      }
docs: List all certificates associated with a certificate order.
  List all certificates associated with a certificate order.
  
  @param resourceGroupName Name of the resource group to which the resource belongs.
  @param certificateOrderName Name of the certificate order.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;AppServiceCertificateResourceInner&gt; object