+ /* We use atomic ref counting here since sd_bus_message
+ objects retain references to their originating sd_bus but
+ we want to allow them to be processed in a different
+ thread. We won't provide full thread safety, but only the
+ bare minimum that makes it possible to use sd_bus and
+ sd_bus_message objects independently and on different
+ threads as long as each object is used only once at the
+ same time. */
+ RefCount n_ref;
+