@SuppressWarnings("NullableProblems")
    @Override
    public Set<Entry<String, String>> entrySet() {
        final Set<Entry<String, String>> rtnSet = new HashSet<>();
        for (final Entry<CIString, String> entry : realMap.entrySet()) {
            rtnSet.add(new CIEntryAdaptor(entry));
        }
        return rtnSet;
    }
String hash map that does not care about key case.
stroom-util/src/main/java/stroom/util/CIStringHashMap.java