public static void start(String userKey) {
        if ((task == null || task.isDone()) & !userKey.isEmpty()) {
            final TestsChecker testsChecker = new TestsChecker(userKey, notification);
            task = scheduler.scheduleAtFixedRate(testsChecker, 30, 30, TimeUnit.SECONDS);
            BmLog.info("TestListController is started with userKey=" + userKey);
        }
    }