The BSD 4-clauses seems like it's not really a good license for this kind of repository, since the whole purpose of the external app system in the beginning was to avoid licensing problems with software using the GNU GPL.
Since this license is incompatible with the GNU GPL, I would suggest to change it for a BSD 3-clauses, which is compatible with said GNU GPL. An even better license would be a MIT license, since it's better suited for thins kind of boilerplate repositories (or even public domain, but I don't think this is ever going to happen).
The BSD 4-clauses seems like it's not really a good license for this kind of repository, since the whole purpose of the external app system in the beginning was to avoid licensing problems with software using the GNU GPL.
Since this license is incompatible with the GNU GPL, I would suggest to change it for a BSD 3-clauses, which is compatible with said GNU GPL. An even better license would be a MIT license, since it's better suited for thins kind of boilerplate repositories (or even public domain, but I don't think this is ever going to happen).