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 static final String ACTIVE_SHARDS_PERCENT_AS_NUMBER = "active_shards_percent_as_number";
    private static final String ACTIVE_PRIMARY_SHARDS = "active_primary_shards";

    public static void sleep(final long millis) {
        if (millis < 1L) {
            return;
        }
        try {
            Thread.sleep(millis);
        } catch (final InterruptedException e) {
            throw new InterruptedRuntimeException(e);
        }
    }

    public static void sleepQuietly(final long millis) {
        if (millis < 1L) {
            return;
        }
        try {