public Set<String> checkpointTopics() throws InterruptedException {
        return listTopics().stream()
            .filter(this::isCheckpointTopic)
            .collect(Collectors.toSet());
    }
@Test
    public void checkpointsTopicsTest() throws InterruptedException {
        MirrorClient client = new FakeMirrorClient(Arrays.asList("topic1", "topic2", "checkpoints.internal",
            "source1.checkpoints.internal", "source2.source1.checkpoints.internal", "source3.checkpoints.internal"));
        Set<String> checkpointTopics = client.checkpointTopics();
        assertEquals(new HashSet<>(Arrays.asList("source1.checkpoints.internal",
            "source2.source1.checkpoints.internal", "source3.checkpoints.internal")), checkpointTopics);
    }