Infer property type if not null I have a function like the following: fun getCommonItemsFrom(element: Element): List? = if (element.parent is CommonElementWrapper) element.items else null So let's assume that Element has a property called parent, which is of type ElementWrapper? (an interface). And this property may or may not be a concrete instance of CommonElementWrapper. This function returns the items (that is non-nullable List) of an Element, as long as the parent property is an instance of...