anchor.diff:      if (disabled) {
         return groupAriaLabel;
       } else {
  -      return _isExpanded ? closePanelMsg : openPanelMsg;
  +      return isExpanded ? closePanelMsg : openPanelMsg;
       }
     }
   
  
positive.code:   @Input()
    bool closeOnSave = true;
  
    bool _isExpanded = false;
    bool get isExpanded => _isExpanded;
  
    /// If true, the panel is expanded by default, if false, the panel is closed.
    @Input('expanded')
    set isExpanded(bool value) {
      if (value == _isExpanded) return;
      if (value) {
        expand(byUserAction: false);
      } else {
  
negative.code:     _changeDetector.markForCheck();
      final stateWasInitialized = initialized;
      actionCtrl.execute(() {
        _isExpanded.value = false;
        _isExpandedChangeByUserAction.add(false);
        _changeDetector.markForCheck();
        if (stateWasInitialized) _transitionHeightChange(false);
  