Hi,
basically that’s the forum post I found http://forums.debian.net/viewtopic.php?f=10&t=143220#p706441
Depending on the base image you are running, you might need to adjust the Debain source file. For Raspberry Pi, it would be
https://download.opensuse.org/repositories/home:/stevenpusser:/xfce-4.14/Raspbian_10/