@VisibleForTesting
  public void doSampling(long millisSinceLastSample) {
    for (ExecutionStateTracker tracker : activeTrackers) {
      tracker.takeSample(millisSinceLastSample);
    }
  }
@Test
  public void testLullDetectionOccurs() throws Exception {
    ExecutionStateTracker tracker1 = createTracker();
    try (Closeable t1 = tracker1.activate(new Thread())) {
      try (Closeable c = tracker1.enterState(step1act1)) {
        sampler.doSampling(TimeUnit.MINUTES.toMillis(6));
      }
    }

    assertThat(step1act1.lullReported, equalTo(true));
  }