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

nesting-simple.kt

// Arrange
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()

// This is straightforward but it won't work
if (parentObj.child?.child?.child?.isValid) {
//   Error.
//   Type mismatch. Required: Boolean, Found: Boolean?
}

// So you need to workaround this
if (parentObj.child?.child?.child?.isValid == true) {
   // Do something
}

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