assertNull(sentIndex.get());

        sentIndex.set(null);
        sentDocList.clear();
        docList.add(new HashMap<>(Map.of(//
                "_id", "001", //
                "config_id", "W01", //
                "url", "http://test.com/001"//
        )));
        docList.add(new HashMap<>(Map.of(//
                "_id", "002", //
                "thumbnail", "http://test.com/002", //

        CrawlingConfig config2 = crawlingConfigHelper.getCrawlingConfig("W01");
        assertEquals("01", config2.getId());

        // After refresh, should get new version
        crawlingConfigHelper.refresh();
        CrawlingConfig config3 = crawlingConfigHelper.getCrawlingConfig("W01");
        assertEquals("01_refreshed", config3.getId());
    }

    @Test