MultiChildRenderObjectWidget constructor

MultiChildRenderObjectWidget({Key key, List<Widget> children: const [] })

Initializes fields for subclasses.

The children argument must not be null and must not contain any null objects.

Implementation 

MultiChildRenderObjectWidget({ Key key, this.children = const <Widget>[] })
  : assert(children != null),
    assert(!children.any((Widget child) => child == null)), // https://github.com/dart-lang/sdk/issues/29276
    super(key: key);