In src/zabbix_server/httppoller/httptest.c, lines 556-562 we disable http headers from the response for no apparent reason.

https://github.com/zabbix/zabbix/blob/trunk/src/zabbix_server/httppoller/httptest.c#L556-L562

It would be useful to be able to regex http headers too to check for matching strings when monitoring a web app.