code: public ServiceFuture<LocalNetworkGatewayInner> getByResourceGroupAsync(String resourceGroupName, String localNetworkGatewayName, final ServiceCallback<LocalNetworkGatewayInner> serviceCallback) {
          return ServiceFuture.fromResponse(getByResourceGroupWithServiceResponseAsync(resourceGroupName, localNetworkGatewayName), serviceCallback);
      }
docs: Gets the specified local network gateway in a resource group.
  
  @param resourceGroupName The name of the resource group.
  @param localNetworkGatewayName The name of the local network 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