/usr/lib/sysusers.d/dbus.conf is in dbus 1.12.2-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | # sysusers.d snippet for creating the D-Bus system user automatically
# at boot on systemd-based systems that ship with an unpopulated
# /etc. See sysusers.d(5) for details.
u messagebus - "System Message Bus"
|