/usr/share/applications/screensavers/fireworkx.desktop is in xscreensaver-data-extra 5.34-2ubuntu1.
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 | [Desktop Entry]
Name=Fireworkx
Exec=/usr/lib/xscreensaver/fireworkx -root
TryExec=/usr/lib/xscreensaver/fireworkx
Comment=Exploding fireworks. See also the "Eruption", "XFlame" and "Pyro" screen savers. Written by Rony B Chandran.
StartupNotify=false
Terminal=false
Type=Application
Categories=Screensaver;
OnlyShowIn=MATE;
|