1. override
String toString()

Returns a human understandable name.

Source 

@override
String toString() {
  String header = '$runtimeType';
  if (_relayoutBoundary != null && _relayoutBoundary != this) {
    int count = 1;
    RenderObject target = parent;
    while (target != null && target != _relayoutBoundary) {
      target = target.parent;
      count += 1;
    }
    header += ' relayoutBoundary=up$count';
  }
  if (_needsLayout)
    header += ' NEEDS-LAYOUT';
  if (!attached)
    header += ' DETACHED';
  return header;
}