message. The copy is a deep copy and the returned
GDBusMessage is completely identical except that it is guaranteed
to not be locked.
This operation can fail if e.g.
message contains file descriptors
and the per-process or system-wide open files limit is reached.
Available since: 2.26
error is set.
Free with g_object_unref().
|The caller of the method takes ownership of the data, and is responsible for freeing it.|