pagingDataFlow
abstract fun pagingDataFlow(pagingConfig: PagingConfig, bookshelf: Bookshelf, file: File, searchCondition: () -> SearchCondition): Flow<PagingData<File>>
abstract fun pagingDataFlow(pagingConfig: PagingConfig, bookshelfId: BookshelfId?, searchCondition: () -> SearchCondition): Flow<PagingData<File>>