How To Set GameEngine In DefaultEngine.ini when the UGameEngine subclass was writen in a plugin?

I know I can write like this when I write not in plugin.but when I write my UGameEngine subclass In plugin ,it not work.I hope someone know how to do ,I see the config write way is not real path so I do not know the right way.
[/Script/Engine.Engine]
GameEngine=/Script/MyUeProject.MyGameEngine