gradient property
Customize the visual appearance of this Foil.
If isUnwrapped is true, this Foil's gradient will be
deactivated, smoothly transitioning to an invisible state.
- Override the unwrapped-state
Gradientwith unwrappedGradient.
It is recommended to use a Gradient that starts and ends
with the same Color.
- LinearSteps or the other
Stepsgradients could handle this aspect.
This Gradient will intrinsically animate to any changed gradient
value by Gradient.lerp over duration and curve.
Using a Roll of Foil
Optionally a Roll may be deployed higher up in the widget tree.
Declare a Roll.gradient to which any descendent Foil may fallback,
though this gradient will override any provided by a Roll.
Pre-rolled Foils
Consider some pre-rolled Foils that come with this package.
The default is Foils.linearLooping if this Foil is not given
a gradient and no ancestral Roll provides one either.

Implementation
final Gradient? gradient;