The ASF.json file, all the options are documented here. Do note that AutoRestart and UpdateChannel is always to false respectively 0 because NixOS takes care of updating everything. Headless is also always set to true because there is no way to provide inputs via a systemd service. You should try to keep ASF up to date since upstream does not provide support for anything but the latest version and you're exposing yourself to all kinds of issues - as is outlined here.
Declarations
Type
JSON valueDefault
{ }Example
{
Statistics = false;
}