docs: public Observable<ServiceResponse<Page<RecordSetInner>>> listAllByDnsZoneSinglePageAsync(final String resourceGroupName, final String zoneName) {
          if (resourceGroupName == null) {
              throw new IllegalArgumentException("Parameter resourceGroupName is required and cannot be null.");
          }
          if (zoneName == null) {
              throw new IllegalArgumentException("Parameter zoneName is required and cannot be null.");
          }
          if (this.client.subscriptionId() == null) {
              throw new IllegalArgumentException("Parameter this.client.subscriptionId() is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          final Integer top = null;
          final String recordSetNameSuffix = null;
          return service.listAllByDnsZone(resourceGroupName, zoneName, this.client.subscriptionId(), top, recordSetNameSuffix, this.client.apiVersion(), this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<Page<RecordSetInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<RecordSetInner>>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<PageImpl<RecordSetInner>> result = listAllByDnsZoneDelegate(response);
                          return Observable.just(new ServiceResponse<Page<RecordSetInner>>(result.body(), result.response()));
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }