Kotlin nullability information in PSI / UAST Follow

Given the following class definition in a project:

class Bar<T>(t: T) {}

What is the correct way to query whether the constructor parameter of Bar<Foo> is nullable via the Psi and/or UAST API?

For instance:

class Foo {

    fun foo(): Bar<String?> {...}
}

How would I be able to determine whether the constructor parameter of type Bar<String?> is nullable?

I haven't been able to find a way to inspect the methods of a class while retaining the type argument nullability information from the initial type reference. Any help would be appreciated. Thanks!