@Override
    public String toString() {
        TreeMap<String, String> outputMap = new TreeMap<>();
        emptyLogDirs.forEach(e -> outputMap.put(e, "EMPTY"));
        errorLogDirs.forEach(e -> outputMap.put(e, "ERROR"));
        logDirProps.forEach((key, value) -> outputMap.put(key, value.toString()));
        return "MetaPropertiesEnsemble" +
            "(metadataLogDir=" + metadataLogDir +
            ", dirs={" + outputMap.entrySet().stream().
            map(e -> e.getKey() + ": " + e.getValue()).
            collect(Collectors.joining(", ")) +
            "})";
    }
Find the cluster ID of this meta.properties ensemble.

@return  The cluster ID, or Optional.empty if none could be found.
metadata/src/main/java/org/apache/kafka/metadata/properties/MetaPropertiesEnsemble.java