borderFillGradients method
Implementation
@override
List<Gradient?> borderFillGradients() {
List<Gradient?> rst = [];
rst.addAll(List.generate(3, (index) => borderSides.top.gradient));
rst.addAll(List.generate(3, (index) => borderSides.right.gradient));
rst.addAll(List.generate(3, (index) => borderSides.bottom.gradient));
rst.addAll(List.generate(3, (index) => borderSides.left.gradient));
return rotateList(rst, 2).cast<Gradient?>();
}