Code review comment: nit: there is a static import for `empty` but not for `is`

Code under review:
public void testFailingJobRecovery() throws Exception {
		final FiniteDuration timeout = new FiniteDuration(10, TimeUnit.SECONDS);
		final FiniteDuration jobRecoveryTimeout = new FiniteDuration(0, TimeUnit.SECONDS);
		Deadline deadline = new FiniteDuration(1, TimeUnit.MINUTES).fromNow();
		final Configuration flinkConfiguration = new Configuration();
		UUID leaderSessionID = UUID.randomUUID();
		ActorRef jobManager = null;
		JobID jobId1 = new JobID();
		JobID jobId2 = new JobID();

		
		flinkConfiguration.setString(HighAvailabilityOptions.HA_MODE, "zookeeper");

		try {
			final SubmittedJobGraphStore submittedJobGraphStore = mock(SubmittedJobGraphStore.class);

			SubmittedJobGraph submittedJobGraph = mock(SubmittedJobGraph.class);
			when(submittedJobGraph.getJobId()).thenReturn(jobId2);

			when(submittedJobGraphStore.getJobIds()).thenReturn(Arrays.asList(jobId1, jobId2));

			
			when(submittedJobGraphStore.recoverJobGraph(eq(jobId1))).thenThrow(new Exception("Test exception"));
			
			when(submittedJobGraphStore.recoverJobGraph(eq(jobId2))).thenReturn(submittedJobGraph);

			final TestingLeaderElectionService myLeaderElectionService = new TestingLeaderElectionService();

			final Collection<JobID> recoveredJobs = new ArrayList<>(2);

			BlobServer blobServer = mock(BlobServer.class);
			Props jobManagerProps = Props.create(
				TestingFailingHAJobManager.class,
				flinkConfiguration,
				TestingUtils.defaultExecutor(),
				TestingUtils.defaultExecutor(),
				mock(InstanceManager.class),
				mock(Scheduler.class),
				blobServer,
				new BlobLibraryCacheManager(blobServer, FlinkUserCodeClassLoaders.ResolveOrder.CHILD_FIRST, new String[0]),
				ActorRef.noSender(),
				new FixedDelayRestartStrategy.FixedDelayRestartStrategyFactory(Int.MaxValue(), 100),
				timeout,
				myLeaderElectionService,
				submittedJobGraphStore,
				mock(CheckpointRecoveryFactory.class),
				jobRecoveryTimeout,
				UnregisteredMetricGroups.createUnregisteredJobManagerMetricGroup(),
				recoveredJobs).withDispatcher(CallingThreadDispatcher.Id());

			jobManager = system.actorOf(jobManagerProps);

			final TestProbe testProbe = new TestProbe(system);

			testProbe.watch(jobManager);

			Future<Object> started = Patterns.ask(jobManager, new Identify(42), deadline.timeLeft().toMillis());

			Await.ready(started, deadline.timeLeft());

			
			myLeaderElectionService.isLeader(leaderSessionID);

			
			assertThat(recoveredJobs, Matchers.is(empty()));

			
			testProbe.expectTerminated(jobManager, timeout);
		} finally {
			TestingUtils.stopActor(jobManager);
		}
	}

Line commented on: assertThat(recoveredJobs, Matchers.is(empty()));

Revised code:
public void testFailingJobRecovery() throws Exception {
		final FiniteDuration timeout = new FiniteDuration(10, TimeUnit.SECONDS);
		final FiniteDuration jobRecoveryTimeout = new FiniteDuration(0, TimeUnit.SECONDS);
		Deadline deadline = new FiniteDuration(1, TimeUnit.MINUTES).fromNow();
		final Configuration flinkConfiguration = new Configuration();
		UUID leaderSessionID = UUID.randomUUID();
		ActorRef jobManager = null;
		JobID jobId1 = new JobID();
		JobID jobId2 = new JobID();

		
		flinkConfiguration.setString(HighAvailabilityOptions.HA_MODE, "zookeeper");

		try {
			final SubmittedJobGraphStore submittedJobGraphStore = mock(SubmittedJobGraphStore.class);

			SubmittedJobGraph submittedJobGraph = mock(SubmittedJobGraph.class);
			when(submittedJobGraph.getJobId()).thenReturn(jobId2);

			when(submittedJobGraphStore.getJobIds()).thenReturn(Arrays.asList(jobId1, jobId2));

			
			when(submittedJobGraphStore.recoverJobGraph(eq(jobId1))).thenThrow(new Exception("Test exception"));
			
			when(submittedJobGraphStore.recoverJobGraph(eq(jobId2))).thenReturn(submittedJobGraph);

			final TestingLeaderElectionService myLeaderElectionService = new TestingLeaderElectionService();

			final Collection<JobID> recoveredJobs = new ArrayList<>(2);

			BlobServer blobServer = mock(BlobServer.class);
			Props jobManagerProps = Props.create(
				TestingFailingHAJobManager.class,
				flinkConfiguration,
				TestingUtils.defaultExecutor(),
				TestingUtils.defaultExecutor(),
				mock(InstanceManager.class),
				mock(Scheduler.class),
				blobServer,
				new BlobLibraryCacheManager(blobServer, FlinkUserCodeClassLoaders.ResolveOrder.CHILD_FIRST, new String[0]),
				ActorRef.noSender(),
				new FixedDelayRestartStrategy.FixedDelayRestartStrategyFactory(Int.MaxValue(), 100),
				timeout,
				myLeaderElectionService,
				submittedJobGraphStore,
				mock(CheckpointRecoveryFactory.class),
				jobRecoveryTimeout,
				UnregisteredMetricGroups.createUnregisteredJobManagerMetricGroup(),
				recoveredJobs).withDispatcher(CallingThreadDispatcher.Id());

			jobManager = system.actorOf(jobManagerProps);

			final TestProbe testProbe = new TestProbe(system);

			testProbe.watch(jobManager);

			Future<Object> started = Patterns.ask(jobManager, new Identify(42), deadline.timeLeft().toMillis());

			Await.ready(started, deadline.timeLeft());

			
			myLeaderElectionService.isLeader(leaderSessionID);

			
			assertThat(recoveredJobs, is(empty()));

			
			testProbe.expectTerminated(jobManager, timeout);
		} finally {
			TestingUtils.stopActor(jobManager);
		}
	}