@Override
        public void putAll(Map<? extends K, ? extends IntegerFieldValue> m) {
            for (Map.Entry<?, ?> e : m.entrySet()) {
                map.put(unwrap(e.getKey()), (Integer) unwrap(e.getValue()));
            }
        }
Weighted set MapFieldValue, backed by map of native Java types.
Note: The key type of this is FieldValue, not K.
@author vegardh
document/src/main/java/com/yahoo/document/datatypes/WeightedSet.java