ClusterAlertingService implements InternalAlertingService { @VisibleForTesting synchronized List<AlertListener> getAlertListeners() { return Collections.unmodifiableList(listeners); } ClusterAlertingService(); @Override void useAlertMessaging(AlertMessaging alertMessaging); @Override void sendAlerts(final AlertLevel alertLevel,
      final Instant timestamp,
      final String threadName,
      final long threadId,
      final String formattedMessage,
      final String stackTrace); @Override synchronized void addAlertListener(final DistributedMember member,
      final AlertLevel alertLevel); @Override synchronized boolean removeAlertListener(final DistributedMember member); @Override synchronized boolean hasAlertListener(final DistributedMember member,
      final AlertLevel alertLevel); @Override boolean hasAlertListeners(); @Override String toString();  }
@Test public void alertListenersIsEmptyByDefault() { assertThat(alertingService.getAlertListeners()).isEmpty(); }