public Optional<String> clusterId() {
        for (MetaProperties metaProps : logDirProps.values()) {
            if (metaProps.clusterId().isPresent()) {
                return metaProps.clusterId();
            }
        }
        return Optional.empty();
    }
@Test
    public void testClusterIdForFoo() {
        assertEquals(Optional.of("fooClusterId"), FOO.clusterId());
    }