}
            cb.query().addOrderBy_CreatedTime_Asc();
            cb.fetchFirst(fessConfig.getPageThumbnailQueueMaxFetchSizeAsInteger());
        }).stream().map(entity -> {
            idList.add(entity.getId());
            if (!cleanup) {
                return executorService.submit(() -> process(fessConfig, entity));

     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     * @throws NumberFormatException When the property is not integer.
     */
    Integer getPageThumbnailQueueMaxFetchSizeAsInteger();

    /**
     * Get the value for the key 'page.thumbnail.purge.max.fetch.size'. <br>
     * The value is, e.g. 100 <br>