code: public ServiceFuture<ExpressRouteConnectionListInner> listAsync(String resourceGroupName, String expressRouteGatewayName, final ServiceCallback<ExpressRouteConnectionListInner> serviceCallback) {
          return ServiceFuture.fromResponse(listWithServiceResponseAsync(resourceGroupName, expressRouteGatewayName), serviceCallback);
      }
docs: Lists ExpressRouteConnections.
  
  @param resourceGroupName The name of the resource group.
  @param expressRouteGatewayName The name of the ExpressRoute gateway.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object