rties.add(EnumProperty&lt;ImageRepeat&gt;('repeat', repeat, defaultValue: ImageRepeat.noRepeat));

    // Warn users when the widget is missing but do not show the value.
    properties.add(ObjectFlagProperty&lt;Widget&gt;('widget', widget, ifNull: 'no widget'));

    properties.add(IterableProperty&lt;BoxShadow&gt;(
      'boxShadow',
      boxShadow,
      defaultValue: null,
      style: style,
    ));

    // Getting the value of size throws an exception unless hasSize is true.
    properties.add(Diagno