Material design Spinner using TextInputLayout.OutlinedBox styling

Question

I am currently using Material Design TextInputLayout OutlinedBox as shown below:

Answer 1

I believe that this document isn't showing a Spinner at all. I think it's showing a TextInputLayout with a dropdown icon.

In the Anatomy section, at the Icons subsection, it says

5. Dropdown icon

A dropdown arrow indicates that a text field has a nested selection component.

Now, how you provide the "nested selection component" I'm not sure...