Copyright for preseed source package in Xenial

The Debian installer preseeder is copyright 2004 by Joey Hess
 and others.

Auto-install functionality, integrated from auto-install udebs, was
originally developed by Philip Hands .

This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your option)
any later version.