buf.append('{');

        final boolean ignoreIdleThreads = Constants.TRUE.equalsIgnoreCase(fessConfig.getCrawlerHotthreadIgnoreIdleThreads());
        final TimeValue interval = TimeValue.parseTimeValue(fessConfig.getCrawlerHotthreadInterval(), "crawler.hotthread.interval");
        final int threads = fessConfig.getCrawlerHotthreadThreadsAsInteger();
        final String timeout = fessConfig.getCrawlerHotthreadTimeout();

                DateHistogramAggregationBuilder.DATE_FIELD_UNITS.get(interval.substring("calendar ".length()))
            );
        } else {
            roundingBuilder = Rounding.builder(TimeValue.parseTimeValue(interval, "interval"));
        }
        Rounding rounding = roundingBuilder.timeZone(ZoneId.of(zone)).build();
        switch (rounder) {
            case "java time":