code: public ServiceFuture<List<ApplicationGatewayInner>> listAllAsync(final ListOperationCallback<ApplicationGatewayInner> serviceCallback) {
          return AzureServiceFuture.fromPageResponse(
              listAllSinglePageAsync(),
              new Func1<String, Observable<ServiceResponse<Page<ApplicationGatewayInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<ApplicationGatewayInner>>> call(String nextPageLink) {
                      return listAllNextSinglePageAsync(nextPageLink);
                  }
              },
              serviceCallback);
      }
docs: Gets all the application gateways in a subscription.
  
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object