private List <ITreeNode> GetAllChildTreeNodes(InOperator inOperator, string propertyName) { var allTreeNodes = new List <ITreeNode>(); XPCollection treeNodes = GetTreeNodes(propertyName, inOperator); if (treeNodes != null) { allTreeNodes = treeNodes.Cast <ITreeNode>().ToList().GetAllTreeNodes(); } return(allTreeNodes.Distinct().ToList()); }