regular expression for XG web exceptions

On my UTM firewall I was able to add a web exception like this:
   ^https?://([A-Za-z0-9.-]*\.)?gstatic\.com/

But on XG 18.0.4 if I try to enter this, I get an error "You must enter a valid domain name"

I was able to slightly modify the regex by removing ^https?:// ... so in other words, this:
   ([A-Za-z0-9.-]*\.)?gstatic\.com/

But ... what impact does that have on filtering?

Does it still work whether the user tries to go to http or https? Do I leave the ^ off of the beginning?