code: public ServiceFuture<ExpressRouteGatewayInner> beginCreateOrUpdateAsync(String resourceGroupName, String expressRouteGatewayName, ExpressRouteGatewayInner putExpressRouteGatewayParameters, final ServiceCallback<ExpressRouteGatewayInner> serviceCallback) {
          return ServiceFuture.fromResponse(beginCreateOrUpdateWithServiceResponseAsync(resourceGroupName, expressRouteGatewayName, putExpressRouteGatewayParameters), serviceCallback);
      }
docs: Creates or updates a ExpressRoute gateway in a specified resource group.
  
  @param resourceGroupName The name of the resource group.
  @param expressRouteGatewayName The name of the ExpressRoute gateway.
  @param putExpressRouteGatewayParameters Parameters required in an ExpressRoute gateway PUT operation.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object