Documentation is missing for the validation path referenced in the dev config

[Xe]

I am trying to evaluate Athens for a project, I noticed that there is a validation hook in the default configuration but there is no details on what this is, means or how it is used.

My thought is that by using this, I can create a system that allows me to somehow identify the source of who is requesting a module (for example: a private module attempted to be downloaded by an attacker who does not normally have access) and prevent them from accessing things they should not be allowed to access.