mod_http_oauth2: Validate the OpenID 'prompt' parameter Without support for affecting the login and consent procedure, it seems sensible to inform the client that they can't change anything with this parameter.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_whitelist",

}
s2s_whitelist = {
    "example.org",
}
```