The title is pretty self explaining.

The following code does not render shadow below the Floating Action Button. What can be done to render shadow? Is this feature really not supported even on API 21+?

```
<android.support.design.widget.FloatingActionButton
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:src="@drawable/ic_add"
    android:clickable="true" />

```

Note: Adding `android:elevation` does not add shadow on API 21.

![Example screenshot](https://i.stack.imgur.com/Wb28n.png)

Screenshot taken from the example by dandar3:
<https://github.com/dandar3/android-support-design>