Return location for a gio.UnixFDList or NULL.
A GAsyncResult obtained from the GAsyncReadyCallback passed to g_dbus_proxy_call_with_unix_fd_list().
NULL if error is set. Otherwise a glib.Variant tuple with return values. Free with Variant.unref.
GException on failure.
2.30
Finishes an operation started with g_dbus_proxy_call_with_unix_fd_list().