BUG: extra_groups doesn't accept multiple values

Hello,

I'm reporting a bug in the config processor/parser. The option extra_groups does not accept multiple (list) values. If you put a section like:

service auth-worker {

user  = $default_internal_user

group = $default_internal_group

extra_groups = shadow mail

}

you will get the error message like:

dovecotFatal: service(auth-worker) Group doesn't exist: shadow mail (See service auth-worker { extra_groups } setting)

It is trivial to reproduce - just try to run the dovecot with the section like above, and you will get the error.

Best regards,

Marcin