Man pages matching name getdns_context_set_context_update_callback in section 3:

getdns_context_set_context_update_callback.3.en	debian 10 / libgetdns-dev
getdns_context_set_context_update_callback.3.en	debian 11 / libgetdns-dev
getdns_context_set_context_update_callback.3.en	debian 12 / libgetdns-dev