@edvin the advantage is that the code will be a lot cleaner, because you can always execute the lambda.
This means the lambda can for example be given to an apply, and other than that, y you know the functions are always doing the same.
I haven't found anything where you should not execute another statement where the lambda is null yet.
When they will arise (which I doubt) then we can use a companion object for the default lambda and checking on that object