``` data class Foo( val bar : Baz ) data class ...

# getting-started

[dG]

data class Foo(
   val bar : Baz
)
data class Baz(
   val smth : String
   val zzz : String?
)

How would I enforce zzz not to be null in Foo (and in Foo only)? Can I achieve a non-nullable zzz there?

[diesieben07]

data class Foo(
    val bar : Baz<String>
)
data class Baz<T : String?>(
    val smth : String,
    val zzz : T
)

[dG]

data class Foo(
   override val bar : Baz
) : InterfaceWithBarFromLibrary
data class BazFromLibrary(
   val smth : String
   val zzz : String?
)

Thanks for the answer, Take. I guess my example was too minimal for my usecase

[dG]

I guess I could not do something like that here, especially as Baz is in a library

[diesieben07]

Ah, yes if it's in a library you cannot do it.

[Nikky]

i think you could make a inline class copy of Baz, that replaces zzz to be non nullable and a method to get a actual baz