protected void AddParent(Identity identity) { var parentItem = _workflow.FindWorkflowItemBy(identity); if (parentItem == null) { throw new ParentItemMissingException(string.Format(Resources.Schedulable_item_missing, identity)); } if (Equals(parentItem)) { throw new CyclicDependencyException(string.Format(Resources.Cyclic_dependency, identity)); } _parentItems.Add(parentItem); }