/usr/share/xsessions/Lubuntu.desktop is in lubuntu-default-settings 0.54.
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 | [Desktop Entry]
Name=Lubuntu
Comment=Lubuntu - Lightweight X11 desktop environment based on LXDE
Exec=/usr/bin/lxsession -s Lubuntu -e LXDE
Type=Application
|