I'm declaring this extension functions in the same file as the data class, but I'm unable to use them in other classes

tulio: you need to import to be able to use them

I'm trying to use them on a Java class... Maybe that's the problem

If I remember correctly, extension functions are compiled to static methods with the first param as the receiver.

besides you can use String::isNullOrEmpty

Nice, I will take a look 🙂

other classes in same package?

to use it from java you need to call as static method defined in YourFileNameKt class

I understood Alejandro

maybe they're just not open?

being an instance of Task the first argument to that method

Funnily enough, the extensionFunction(receiver, params...) way of calling an extension function works in both Kotlin and Java

sure, if it works in java makes sense to work in kotlin