@darrelmiller
1. `cache_control_has_revalidate_directive` is a bad name to stand for `Contains must-revalidate/public/s-maxage`. Ideas welcome
2. this is different than your diagram: if the `Cache-Control` contains `must-revalidate/public/s-maxage` isn't it redundant to check if it contains `Expires/max-age/s-maxage/public/other cacheable directive` ?
3. did you notice the s-*maxage* ? It's not s-max*-*age. I guess another `Referer`-like case