final SearchEngineClient searchEngineClient = ComponentUtil.getSearchEngineClient();
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        return searchEngineClient.getDocumentList(fessConfig.getIndexDocumentSearchIndex(),
                searchRequestBuilder -> SearchConditionBuilder
                        .builder(searchRequestBuilder.setPreference(Constants.SEARCH_PREFERENCE_LOCAL))

    protected UpdateRequestBuilder createUpdateRequestBuilder() {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        return ComponentUtil.getSearchEngineClient().prepareUpdate().setIndex(fessConfig.getIndexDocumentSearchIndex());
    }

    protected void flush() {
        if (bulkRequestBuilder != null) {
            final BulkResponse response = bulkRequestBuilder.execute().actionGet(requestTimeout);