Added a couple of notes in the code review:
- mod_http2 does not work with mpm-prefork but only with worker/event (latter is preferred). The mod_http2 prefork support has recently been deprecated. I quickly checked cobalt/gerrit2001 and it seems that we use prefork.
- Since the experimental tag has been removed only recently I strongly suggest to use a recent version of httpd (possibly only debian >= stretch in which we have 2.4.25). On cobalt we are running 2.4.10 that should not be used in my opinion.
- mpm-event (requirements of 1) has got a ton of changes only recently, so another good point to use only a super recent version of httpd.
The above notes assumes that my understanding of where/how gerrit run is correct, that might not be true :)