/etc/xdg/ is in lubuntu-default-settings 0.27.
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/lightdm/
/etc/xdg/lubuntu/lightdm/lightdm-gtk-greeter.conf
/etc/xdg/lubuntu/lxdm/
/etc/xdg/lubuntu/lxdm/lxdm.conf
/etc/xdg/lubuntu/menus/
/etc/xdg/lubuntu/menus/lxde-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/desktop.conf
/etc/xdg/lxsession/Lubuntu/autostart
/etc/xdg/lxsession/Lubuntu/desktop.conf
/etc/xdg/pcmanfm/
/etc/xdg/pcmanfm/lubuntu/
/etc/xdg/pcmanfm/lubuntu/pcmanfm.conf