A while ago I have packaged Softmaker Office and FreeOffice, both are closed source, but are pretty useful (as least to me) because they have fairly good Office compatibility. The derivations work fine, except that they break regularly, because the source tarballs are replaced. E.g., at some point the release version is 972 with the corresponding download URL
https://www.softmaker.net/down/softmaker-office-2018-972-amd64.tgz
Then then Softmaker Office is updated, and not only do they release a new tarball such as:
https://www.softmaker.net/down/softmaker-office-2018-974-amd64.tgz
But the previous version’s tarball is 301-redirected to the new version. Of course, this breaks the derivation until the hash is updated. I asked about this, and they seem to do redirections because people click on links in older release emails:
https://forum.softmaker.com/viewtopic.php?f=320&t=19327&p=63557&hilit=nixos#p63557
They suggest hosting the source tarballs ourselves to avoid that hashes change. Is such a facility available?