ExpandIcon({Key key, bool isExpanded: false, double size: 24.0, @required ValueChanged<bool> onPressed, EdgeInsets padding: const EdgeInsets.all(8.0) })

Creates an ExpandIcon with the given padding, and a callback that is triggered when the icon is pressed.

Source 

ExpandIcon({
  Key key,
  this.isExpanded: false,
  this.size: 24.0,
  @required this.onPressed,
  this.padding: const EdgeInsets.all(8.0)
}) : super(key: key) {
  assert(this.isExpanded != null);
  assert(this.size != null);
  assert(this.padding != null);
}