I've tried this already, but there's config error:
[emerg]: the closing bracket in "cookie_jetbrains" variable is missing in /usr/local/nginx/conf/nginx.conf:178

Also I've tried:
proxy_cache_key "$host$request_uri $cookie_jetbrains\.charisma\.main\.security\.PRINCIPAL";
and with \\ and \\\ before dot, without success. :-(
There no error, but no success too.

Thanks,
Sergey