private void failAllVersionDependentTasks() {
        tasksPendingStateRecompute.forEach(task -> {
            task.handleFailure(RemoteClusterControllerTask.Failure.of(
                    RemoteClusterControllerTask.FailureCondition.LEADERSHIP_LOST));
            task.notifyCompleted();
        });
        tasksPendingStateRecompute.clear();
        taskCompletionQueue.forEach(task -> {
            task.getTask().handleFailure(RemoteClusterControllerTask.Failure.of(
                    RemoteClusterControllerTask.FailureCondition.LEADERSHIP_LOST));
            task.getTask().notifyCompleted();
        });
        taskCompletionQueue.clear();
    }
Called when we can no longer contact database.
clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/FleetController.java