return Arrays.stream(response.getHits().getHits()).map(SearchHit::getId).toArray(n -> new String[n]);
    };

    protected Function<Map<String, Object>, Long> requestHandler = params -> {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final String[] ids = idFinder.apply(params);
        if (ids.length == 0) {
            return 0L;
        }