public OptionalEntity<ProtwordsFile> getProtwordsFile(final String dictId) {
        return dictionaryManager.getDictionaryFile(dictId).filter(ProtwordsFile.class::isInstance)
                .map(file -> OptionalEntity.of((ProtwordsFile) file)).orElse(OptionalEntity.empty());
    }

    public OptionalEntity<ProtwordsItem> getProtwordsItem(final String dictId, final long id) {
        return getProtwordsFile(dictId).map(file -> file.get(id).get());

    public JsonResponse<ApiResult> post$upload(final String dictId, final UploadForm form) {
        form.dictId = dictId;
        validateApi(form, messages -> {});
        final ProtwordsFile file = protwordsService.getProtwordsFile(form.dictId).orElseGet(() -> {
            throwValidationErrorApi(messages -> messages.addErrorsFailedToUploadProtwordsFile(GLOBAL));
            return null;
        });