@VisibleForTesting
  public static Listener getListener() {
    return listenerRef.get();
  }
A message that is sent to an admin member or manager to notify it of an alert.

<p>
Alerts are sent from remote members to the manager via {@link AlertListenerMessage} which is
no-ack (asynchronous). This means you cannot log a warning in one VM and immediately verify that
it arrives in the manager VM. You have to use {@code Mockito#timeout(long)} or
{@code Awaitility}.
geode-core/src/main/java/org/apache/geode/internal/admin/remote/AlertListenerMessage.java