private void FillFolders(TreeNode node) { var folderApi = new IO.Swagger.Api.FoldersApi(Configuration); var folders = folderApi.FoldersGetByParentId(node == null ? 0 : Convert.ToInt32(node.Name)); foreach (var folderDto in folders) { if (node == null) { foldersTree.Nodes.Add(folderDto.Id.ToString(), folderDto.Name); } else { node.Nodes.Add(folderDto.Id.ToString(), folderDto.Name); } } }