ThreadUtil.sleep(interval);
        }).then(response -> {
            refresh();
            success.accept(true);
        }).error(t -> error.accept(t));
    }

    /**
     * Purges old suggest data from documents.
     *
     * @param time The timestamp to purge data before.
     */
    public void purgeDocumentSuggest(final LocalDateTime time) {

            }
            generatorList.add(generator);
        } else if (logger.isDebugEnabled()) {
            logger.debug("{} is not available.", generator.getName());
        }
    }

    /**
     * Purges old thumbnail files based on the expiry time.
     *
     * @param expiry the expiry time threshold
     * @return the number of files purged
     */
    public long purge(final long expiry) {