hoverElevation property Null safety
The elevation for the button's Material when the button is enabled and a pointer is hovering over it.
Defaults to 4.0. The value is always non-negative.
- elevation, the default elevation.
- focusElevation, the elevation when the button is focused.
- disabledElevation, the elevation when the button is disabled.
- highlightElevation, the elevation when the button is pressed.
final double? hoverElevation;