/etc/xdg/lxsession/Lubuntu/autostart is in lubuntu-default-settings 0.27.
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 | @lxpanel --profile Lubuntu
@xscreensaver -no-splash
@xfce4-power-manager
@pcmanfm --desktop --profile lubuntu
@/usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1
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