Map get with null key I'm confused by Kotlin's null safety features when it comes to maps. I have a Map. Yet I can call map.get(null) and it returns null to indicate that the key is not present in the map. I expected a compiler error, because map is a Map and not a Map. How come I can pass null for a String argument? And a related question: is there any type of Map, be it a stdlib one or a third-party implementation, that may throw NullPointerException if I call get(null)? I'm wondering if it is safe to call...