code: public Observable<Page<ApplicationGatewayInner>> listAllAsync() {
          return listAllWithServiceResponseAsync()
              .map(new Func1<ServiceResponse<Page<ApplicationGatewayInner>>, Page<ApplicationGatewayInner>>() {
                  @Override
                  public Page<ApplicationGatewayInner> call(ServiceResponse<Page<ApplicationGatewayInner>> response) {
                      return response.body();
                  }
              });
      }
docs: Gets all the application gateways in a subscription.
  
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;ApplicationGatewayInner&gt; object