/usr/lib/tmpfiles.d/dbus.conf is in dbus 1.10.6-1ubuntu3.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | # Type Path Mode UID GID Age Argument
L /var/lib/dbus/machine-id - - - - /etc/machine-id
|