1. override
MaxTileWidthGridDelegate createDelegate()

The delegate that controls the layout of the children.

Source 

@override
MaxTileWidthGridDelegate createDelegate() {
  return new MaxTileWidthGridDelegate(
    maxTileWidth: maxTileWidth,
    tileAspectRatio: tileAspectRatio,
    columnSpacing: columnSpacing,
    rowSpacing: rowSpacing,
    padding: padding
  );
}