Hi guys, I want to know if this is a bug or anyone can explain this. The setValue is okay with this error, but why the getValue don't give me the same error?

We can't see what is the actual error in your screenshot. BTW, you could use

ReadWriteProperty

from Kotlin stdlib here

@louiscad a create a Interface just for Nullable types with Generic types, but, when a I use it, just the setValue the Compiler is forcing to be nullable and the getValue not, this is the problem.

You could try with

out

variance on the type parameter of the interface. I don't see the code on

setValue

though, so I can't help much…