@VisibleForTesting
  boolean hasApplication(ApplicationId appId) {
    return collectorManager.containsTimelineCollector(appId);
  }
@Test
  void testAddApplication() throws Exception {
    auxService = createCollectorAndAddApplication();
    // auxService should have a single app
    assertTrue(auxService.hasApplication(appAttemptId.getApplicationId()));
    auxService.close();
  }