categorize the exchange folders in Distinguished Folder and normal folder

Question

My question is how to make difference between a distinguished folders and a folder created by user when i try to obtain the list of user folders using findFolder ws method

    FindFolderType request = new FindFolderType();

    request.setTraversal(FolderQueryTraversalType.DEEP);

    FolderResponseShapeType folderResponseShapeType = new FolderResponseShapeType();
    folderResponseShapeType.setBaseShape(DefaultShapeNamesType.ALL_PROPERTIES);
    request.setFolderShape(folderResponseShapeType);

    NonEmptyArrayOfBaseFolderIdsType folderIds = new NonEmptyArrayOfBaseFolderIdsType();
    DistinguishedFolderIdType folderId = new DistinguishedFolderIdType();
    folderId.setId(DistinguishedFolderIdNameType.MSGFOLDERROOT);
    folderIds.getFolderIdOrDistinguishedFolderId().add(folderId);
    request.setParentFolderIds(folderIds);


    //response
    Holder<FindFolderResponseType> findFolderResult = new Holder<FindFolderResponseType>();

    addHandlers(port);

    port.findFolder(
            request,
            getImpersonation(smtpAddress),
            getSerializedSecurityContextType(),
            MAILBOX_CULTURE,
            getServerVersion(),
            findFolderResult,
            serverVersion);

i can not see any property to distinct between these 2 types of folders

Thank you