Paradox, can we get some info about unused triggers/effects

[Jormarn]

Dear Paradox team,
there are several triggers and effects currently in Stellaris that are unused in the main game. It would be amazing to get some information how and whether they work.

Example:
The effect

 declare_white_peace_with

is mentioned in the doc dump with the mention that its scope is "country". But how to use it ?
I tried

parameter:country = {
                every_war_defender = {
                    limit = { 
                        any_war_attacker = {
                            is_country = parameter:country
                        }
                    }
                    declare_white_peace_with =  PREV
                    # parameter:country = {     #this alternative also does nothing
                        # declare_white_peace_with =  PREV
                    # }
                    
                }
}

and there is no error in the log. But there is also nothing happening and I have no idea why.

Actually most of the "war" effects and triggers are not really used in the game right now, but present in the doc dump.
Or does anyone else know how this works or where my error is ?

Regards, Jormarn