Mojang version.json files never get re-validated

[Pyker]

Like the title says, Mojang version.json files never get re-validated. By "Mojang version.json files" I mean the Minecraft version info files, like this one: https://launchermeta.mojang.com/v1/packages/3268559d83cffc8687ed3e282c1edb0d72ed6e75/1.16.json

When a modpack is installed/reinstalled (or updated, which triggers a reinstall), the file matching the modpack's MC version is downloaded from our mirror, but that file never actually gets revalidated. There's no hash checking (there isn't a hash to begin with), no ETag checking, no "If-Modified-Since" checking. But there needs to be. Sometimes updates are pushed out by Mojang to already-released versions (usually to update the asset index).