@Override
  protected void sendHealthCheck() {
    send(HEALTH_CHECK_REQUEST);
  }
@Test
  public void testSendHealthCheck() {
    TestGetWorkMetadataRequestObserver requestObserver =
        Mockito.spy(new TestGetWorkMetadataRequestObserver());
    GetWorkerMetadataTestStub testStub = new GetWorkerMetadataTestStub(requestObserver);
    stream = getWorkerMetadataTestStream(testStub, 0, new TestWindmillEndpointsConsumer());
    stream.sendHealthCheck();

    verify(requestObserver).onNext(WorkerMetadataRequest.getDefaultInstance());
  }