Gap

gap.dart

class Gap extends LeafRenderObjectWidget {
  const Gap(
    this.mainAxisExtent, {
    Key key,
  })  : assert(mainAxisExtent != null &&
            mainAxisExtent >= 0 &&
            mainAxisExtent < double.infinity),
        super(key: key);

  final double mainAxisExtent;

  @override
  RenderObject createRenderObject(BuildContext context) {
    return _RenderGap(mainAxisExtent: mainAxisExtent);
  }

  @override
  void updateRenderObject(BuildContext context, _RenderGap renderObject) {
    renderObject.mainAxisExtent = mainAxisExtent;
  }
}