Practice: Classes and Collections: Android Basics with Compose - Task 7

[Akronix]

If I use the solution for task 7:

val Event.durationOfEvent: String
                	get() = if (this.durationInMinutes < 60) {"short"} else {"long"}

I get:
Unresolved reference 'durationOfEvent'.
when calling to println("Duration of first event of the day: ${events[0].durationOfEvent}").

However, if I remove the Event. part in the extension property (so it's an extension of the objects and not of a class property),

val durationOfEvent: String
                	get() = if (this.durationInMinutes < 60) {"short"} else {"long"}

now it works correctly:
Duration of first event of the day: short