public void persistInstanceLabels(final String instanceId, final Collection<String> labels) {
        repository.persistEphemeral(ComputeNode.getInstanceLabelsNodePath(instanceId), YamlEngine.marshal(labels));
    }
@Test
    void assertPersistInstanceLabels() {
        ComputeNodePersistService computeNodePersistService = new ComputeNodePersistService(repository);
        InstanceMetaData instanceMetaData = new ProxyInstanceMetaData("foo_instance_id", 3307);
        final String instanceId = instanceMetaData.getId();
        computeNodePersistService.persistInstanceLabels(instanceId, Collections.singletonList("test"));
        verify(repository).persistEphemeral(ComputeNode.getInstanceLabelsNodePath(instanceId), YamlEngine.marshal(Collections.singletonList("test")));
        computeNodePersistService.persistInstanceLabels(instanceId, Collections.emptyList());
        verify(repository).persistEphemeral(ComputeNode.getInstanceLabelsNodePath(instanceId), YamlEngine.marshal(Collections.emptyList()));
    }