private static SortedMap<String, Collection<String>> copyExtraAttributes(Map<String, Collection<String>> extraAttributes) {
        SortedMap<String, Collection<String>> copy = new TreeMap<>();
        extraAttributes.forEach((key, value) -> copy.put(key, new ArrayList<>(value)));
        return copy;
    }
A immutable request log entry

@author bjorncs
container-core/src/main/java/com/yahoo/container/logging/RequestLogEntry.java