Save comments in config.yml with api spigot/bukkit

I have a config.yml file that has some comments like:

#Thats the message when someone joins to the serverMessage: Hello User

But when I save the config.yml file and open again it vanishes and can't be saved.

I tried to search some api for this problem but could not find.I dont want to use

saveDefaultConfig();

or

getConfig().options.copydefault(true);saveConfig();

because I dont want to save this trough code. I want to save this with api.

What api should I use?