/etc/xdg/ is in lubuntu-default-settings 0.54.
This file is owned by root:root, with mode 0o755.
..
/etc/xdg/lubuntu/
/etc/xdg/lubuntu/applications/
/etc/xdg/lubuntu/applications/defaults.list
/etc/xdg/lubuntu/libfm/
/etc/xdg/lubuntu/libfm/libfm.conf
/etc/xdg/lubuntu/lxdm/
/etc/xdg/lubuntu/lxdm/lxdm.conf
/etc/xdg/lubuntu/lxterminal/
/etc/xdg/lubuntu/lxterminal/lxterminal.conf
/etc/xdg/lubuntu/menus/
/etc/xdg/lubuntu/menus/lxde-applications.menu
/etc/xdg/lubuntu/menus/lxgames-applications.menu
/etc/xdg/lxsession/
/etc/xdg/lxsession/Lubuntu/
/etc/xdg/lxsession/Lubuntu-Netbook/
/etc/xdg/lxsession/Lubuntu-Netbook/autostart
/etc/xdg/lxsession/Lubuntu-Netbook/conffiles.conf
/etc/xdg/lxsession/Lubuntu-Netbook/desktop.conf
/etc/xdg/lxsession/Lubuntu/autostart
/etc/xdg/lxsession/Lubuntu/conffiles.conf
/etc/xdg/lxsession/Lubuntu/desktop.conf
/etc/xdg/pcmanfm/
/etc/xdg/pcmanfm/lubuntu/
/etc/xdg/pcmanfm/lubuntu/desktop-items-0.conf
/etc/xdg/pcmanfm/lubuntu/pcmanfm.conf
/etc/xdg/xdg-Lubuntu/
/etc/xdg/xdg-Lubuntu/dhcpcd.conf
/etc/xdg/xdg-Lubuntu/lxqt/
/etc/xdg/xdg-Lubuntu/lxqt/lxqt.conf
/etc/xdg/xdg-Lubuntu/lxqt/notifications.conf
/etc/xdg/xdg-Lubuntu/lxqt/panel.conf
/etc/xdg/xdg-Lubuntu/lxqt/session.conf
/etc/xdg/xdg-Lubuntu/lxqt/windowmanagers.conf
/etc/xdg/xdg-Lubuntu/menu/
/etc/xdg/xdg-Lubuntu/menu/lxqt-applications.menu
/etc/xdg/xdg-Lubuntu/openbox/
/etc/xdg/xdg-Lubuntu/openbox/lxqt-rc.xml
/etc/xdg/xdg-Lubuntu/xfce4/
/etc/xdg/xdg-Lubuntu/xfce4/xfconf/
/etc/xdg/xdg-Lubuntu/xfce4/xfconf/xfce-perchannel-xml/
/etc/xdg/xdg-Lubuntu/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml
/etc/xdg/xdg-QLubuntu