Tracking issue for @lmolkova's #373 (comment):

One thing we can consider is to require network.transport presence for HTTP/3 if it's known for sure

I.e. change "If not default (tcp for HTTP/1.1 and HTTP/2, udp for HTTP/3)."

to

"If not default (tcp for HTTP/1.1 and HTTP/2). MUST be set for HTTP/3 if it is known"

This way, a lack of protocol would mean a lack of information (and not default value). We should still be able to change the condition in the future if we'd have reliable ways to determine the protocol.

currently: