copyright holders unclear for icons/protocol files

Dear,

While working on Debian packaging for chatty together with the DebianOnMobile team, we noticed that the 3 files under data/icons/protocol do not have their copyright holders clearly identified. As we cannot be sure regarding the origin of those files, we cannot document that properly under debian/copyright which is a hard pre-requisite for a software to be accepted into Debian.

Current workaround is to strip those 3 files away but ideally we would like to keep those files and update debian/copyright to mention their copyright holders and the license used to release those files.

Could you please let us know where those files are coming from so we can take it from there?

Thanks and best regards,