Return location for a #GUnixFDList or %NULL.
A #GAsyncResult obtained from the #GAsyncReadyCallback passed to g_dbus_proxy_call_with_unix_fd_list().
Return: %NULL if @error is set. Otherwise a #GVariant tuple with return values. Free with g_variant_unref().
GException on failure.
2.30
Finishes an operation started with g_dbus_proxy_call_with_unix_fd_list().