private static final String NUMBER_OF_DATA_NODES = "number_of_data_nodes";
    private static final String NUMBER_OF_PENDING_TASKS = "number_of_pending_tasks";
    private static final String NUMBER_OF_IN_FLIGHT_FETCH = "number_of_in_flight_fetch";
    private static final String DELAYED_UNASSIGNED_SHARDS = "delayed_unassigned_shards";
    private static final String TASK_MAX_WAIT_TIME_IN_QUEUE_IN_MILLIS = "task_max_waiting_in_queue_millis";

    }

    private void assertImageSize(File file, int width, int height) throws IOException {
        BufferedImage img = ImageIO.read(file);
        logger.debug("width: {}, height: {}", img.getWidth(), img.getHeight());
        assertEquals("Image Width", width, img.getWidth());
        assertEquals("Image Height", height, img.getHeight());
    }

                final int width = reader.getWidth(0);
                final int height = reader.getHeight(0);
                if (width <= 0 || height <= 0) {
                    return Result.NO_IMAGE;
                }
                if (!fessConfig.validateThumbnailSize(width, height)) {
                    return Result.INVALID_SIZE;
                }