License header in each file

[wadoon]

We already discussed the topic of header files. I found in an old branch that we had used

/*
 * This file is part of KeY - https://key-project.org
 * KeY is licensed by the GNU General Public License Version 2
 * SPDX-License-Identifier: GPL-2.0
 */

[FliegendeWurst]

I think GPL-2.0 should be GPL-2.0-or-later.

See

key/LICENSE.TXT

Lines 38 to 39 in 0ac6d7f

	Foundation; either version 2 of the License, or (at your
	option) any later version.

[wadoon]

This is not possible. KeY was created under GPLv2-only. We do not have the rights to alter the license.