Copyright for retro-gtk source package in Focal

Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: retro-gtk
Source: https://download.gnome.org/sources/retro-gtk/

Files: *
Copyright: 2014-2017 Adrien Plazas 
License: GPL-3
 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, version 3 of the License.
 .
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 .
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see .
 .
 On Debian systems, the complete text of the GNU General
 Public License can be found in `/usr/share/common-licenses/GPL-3'.