Earlier today I gave a short talk about navigating Wireshark's source code. One thing I mentioned is that we have quite a bit of boilerplate at the top and bottom of most files, and in the past this has confused git when copying and renaming files (for me, at least).
I've uploaded a change at
https://code.wireshark.org/review/#/c/24302/ which starts the process of replacing the GPLv2-or-later blurb at the top of various files with "SPDX-License-Identifier: GPL-2.0+". Is there any reason we shouldn't go ahead with this?