.boostMode(CombineFunction.MULTIPLY));
            reader.addSort(SortBuilders.fieldSort(fessConfig.getIndexFieldClickCount()));
            reader.addSort(SortBuilders.scoreSort());
            return reader;
        }, docPerReq, () -> {
            systemHelper.calibrateCpuLoad();
            ThreadUtil.sleep(interval);

            final SearchLogHelper searchLogHelper = ComponentUtil.getSearchLogHelper();
            final int count = searchLogHelper.getClickCount(url);
            doc.put(fessConfig.getIndexFieldClickCount(), count);
            if (logger.isDebugEnabled()) {
                logger.debug("Click Count: {}, url: {}", count, url);
            }
        }
    }

     * The value is, e.g. click_count <br>
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getIndexFieldClickCount();

    /**
     * Get the value for the key 'index.field.config_id'. <br>
     * The value is, e.g. config_id <br>