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kotlinlang

you can at least do things like
```
val a: List&lt;String?&gt;
    val b: List&lt;String&gt;
    a = b
```

List is covariance.
List&lt;String&gt; seems like a subtype of List&lt;String?&gt;

see generics doc.
<http://kotlinlang.org/docs/reference/generics.html>

exactly which proves that String is a subtype of String? :wink:

`String?` can store `String`, that’s all

must be more if `String &lt;: String?` is not true then `List&lt;String&gt; &lt;: List&lt;String?&gt;` would not work