ISPConfig 3.1.11 with nginx and enabling HTTP/2

Hello together,
i found an interesting post where we can make our websites HTTP/2 capable.

https://www.nginx.com/blog/nginx-1-9-5/
Enabling HTTP/2
To enable HTTP/2 support, simply add the http2 parameter to all listen directives. Also include the ssl parameter, required because browsers do not support HTTP/2 without encryption.

server {
listen 443 ssl http2 default_server;
ssl_certificate server.crt;
ssl_certificate_key server.key;
...
}

it should be easy. But for me is the question how ISPConfig handles the making of vhost files:
i bought the manual but i found nothing about the behaviour.
As i know from plesk they have a standard file and for each virtual host you can set directives in admin
ISPConfig i assume does the same, standard file + directives from admin = vhost file located in etc/nginx/sites-enabled, when some error occurs then there lies an .err file which indicates that the code not worked and nginx is started with standard file for that website.
The main reason i searched for another solution apart from plesk is:
in Plesk you cannot set map directives for multishop environments nor set other things on commandline
and in Plesk you can only set location directives in admin, if you inside som mappings then you cannot save configuration.
in ISPConfig my feeling is that its more free you can do much more but as always where you can make more you can make more errors. But i prefer ISPConfig and want to stay.

so back to my question.
how can i set things

what i not have figured out already is why there are to places in admin where i can input directives
one under options (i use already for wordpress and magento) but there is one for redirects the wiki says if clauses are used
http://nginx.org/en/docs/http/ngx_http_rewrite_module.html

ok perhaps someone can tell me where to edit this small thing with
http2
and where to put
map directives like this ones

i cannot imagine that this should be impossible or unwanted like it is in plesk.

I think it goes like this
/etc/nginx/nginx.conf is main file
inside
include /etc/nginx/modules-enabled/*.conf;
modules are called - i have some -

Finally

my conf.d directory is empty
and in sites-enabled all of my sites are listed ok these are symlinks
the files itself are in etc/nginx/sites-enabled

FINAL QUESTION: in which file or in which admin panel should i put these files menioned?

 

Ok thank you, i commented this out to use always http2 and this worked fine..

but after reading some posts in howtoforge i have found an hint that there exists some logic with spdy http2 is considered as its successor.

and i found a checkbox inside regarding http2
do you know if this is working?

 

i want to report, that i removed the if clause in your nginx.conf and set http2 manually global