Why does a ContiguousArrayStorage <String> leak?

Question

Steps to play:

Create a new Xcode project: File -> New Project

Add property: let tags = ["1", "2"] in AppDelegate

Go to product → Profile

Tools show _ContiguousArrayStorage leak?

If you change let tags = ["1", "2"] to let tags = "1" , the leak will disappear.

Can someone explain why [String] is leaking, but String is not working?

Xcode 8.0 (8A218a)