List<Element> children

Source 

List<Element> get children {
  if (_docChildren == null) {
    _docChildren = new FilteredElementList(this);
  }
  return _docChildren;
}
void children=(List<Element> value)

Source 

set children(List<Element> value) {
  // Copy list first since we don't want liveness during iteration.
  var copy = value.toList();
  var children = this.children;
  children.clear();
  children.addAll(copy);
}