return requestHandler.apply(params);
    }

    /**
     * Creates an update request builder.
     * @return The update request builder.
     */
    protected UpdateRequestBuilder createUpdateRequestBuilder() {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        return ComponentUtil.getSearchEngineClient().prepareUpdate().setIndex(fessConfig.getIndexDocumentSearchIndex());
    }

    /**