open class OpenClass
class FirstOpenClass : OpenClass()
class SecondOpenClass : OpenClass()

class Foo<TGen : OpenClass> (
    val open: TGen// = FirstOpenClass() //error
) {
    companion object {
        fun buildFirst() = Foo(FirstOpenClass()) // it's OK
        fun buildSecond() = Foo(SecondOpenClass()) // it's OK
    }
}

class A

class Foo<T>(cons: () -> T) {
    val open by lazy(cons)
}

fun main() {
    val a = Foo(::A).open
}