/// <summary>
 /// Reconstructs the parents for all nodes of this graph. Call this from the root.
 /// Needed since we cannot serialize the parent to json or we will get cyclic dependencies.
 /// </summary>
 /// <param name="parent">The parent of this project item.</param>
 public virtual void BuildParents(FolderItem parent = null)
 {
     this.Parent = parent;
 }