code: public ServiceFuture<LocalNetworkGatewayInner> createOrUpdateAsync(String resourceGroupName, String localNetworkGatewayName, LocalNetworkGatewayInner parameters, final ServiceCallback<LocalNetworkGatewayInner> serviceCallback) {
          return ServiceFuture.fromResponse(createOrUpdateWithServiceResponseAsync(resourceGroupName, localNetworkGatewayName, parameters), serviceCallback);
      }
docs: Creates or updates a local network gateway in the specified resource group.
  
  @param resourceGroupName The name of the resource group.
  @param localNetworkGatewayName The name of the local network gateway.
  @param parameters Parameters supplied to the create or update local network gateway 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