remove nginx from https response header

nginx 1.9.5

I know how to remove or change the "nginx" string in the server field of the response header.
For http traffic modify the ../src/http/ngx_http_header_filter_module.c

But https (http2) traffic seems to be else where, anyone happen to know where? I've looked around, thought I've found once or twice - turned out nope.

Thanks