withPaint method
This pass painted with paint instead — null included, which is "the
text's own colour" and the one value copyWith cannot say, because
there a null means "not given".
Implementation
@override
FillLayer withPaint(ScenePaint? paint) => FillLayer(
paint: paint,
blur: blur,
dx: dx,
dy: dy,
opacity: opacity,
box: box,
blend: blend,
);