1. override
bool shouldRelayout(GridDelegateWithInOrderChildPlacement oldDelegate)

Override this method to return true when the children need to be laid out.

Source 

@override
bool shouldRelayout(GridDelegateWithInOrderChildPlacement oldDelegate) {
  return columnSpacing != oldDelegate.columnSpacing
      || rowSpacing != oldDelegate.rowSpacing
      || padding != oldDelegate.padding;
}