/usr/share/applications/mate-screensaver-lock.desktop is in mate-gnome-main-menu-applet 1.8.0-5build1.
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 6 7 8 9 10 11 | [Desktop Entry]
Name=Lock Screen
Version=1.0
Icon=gnome-lockscreen
Exec=mate-screensaver-command --lock
Terminal=false
Type=Application
Categories=Application;System;
Keywords=MATE;main;menu;lock;screen;
OnlyShowIn=MATE;
Hidden=true
|