public virtual TResult VisitNode(FieldEventNodeViewModel fieldEventNode, TInput input) => DefaultVisit(fieldEventNode, input);
 public virtual TResult VisitNode(FieldEventNodeViewModel fieldEventNode) => DefaultVisit(fieldEventNode);
 public virtual IEnumerable <TreeNodeViewModel> VisitNodeAndBuildChildren(FieldEventNodeViewModel fieldEventNode, bool expandChildren,
                                                                          CancellationToken cancellation) =>
 Enumerable.Empty <TreeNodeViewModel>();