@Override
    public String put(final String key, final String value) {
        if (key != null && StandardHeaderArguments.DATE_HEADER_KEYS.contains(key)) {
            final String normalisedValue = DateUtil.normaliseDate(value, true);
            return super.put(key, normalisedValue);
        } else {
            return super.put(key, value);
        }
    }
Map that does not care about key case.
stroom-meta/stroom-meta-api/src/main/java/stroom/meta/api/AttributeMap.java