For medium article: https://medium.com/@amatkivskiy/legacy-code-pitfalls-35feda5acb71

nesting-complex.kt

data class Parent(val child: Nested?)
class Nested(val child: Nested?, val isValid: Boolean = false)

// Assume you got this object from the dark and deep internals of your app
val parentObj = getParentObjFromInternals()

doSomethingOnBooleanValue(parentObj.child?.child?.child?.isValid)

fun doSomethingOnBooleanValue(valid: Boolean?) {
    if (valid == true) {
        // `valid` is really true
    } else {
        // `valid` is false or null
    }
}

fun getParentObjFromInternals() = Parent(Nested(Nested(Nested(null, true))))