/usr/share/dbus-1/services/org.mate.ScreenSaver.service is in mate-screensaver-common 1.8.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | [D-BUS Service]
Name=org.mate.ScreenSaver
Exec=/usr/bin/mate-screensaver --no-daemon
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