public static void AddSubFolder(FolderDescriptor folder, FolderDescriptor subFolder) { IResource parentFolder = null; if (folder != null) { parentFolder = Find(folder.FolderIDs.EntryId); } IResource resFolder = FindOrCreate(subFolder, parentFolder); if (Folder.IsParentRoot(resFolder) || Folder.IsParentParentRoot(resFolder)) { SetDefault(resFolder, true); } }