public void putAll(Map<? extends K, ? extends V> map) {
        for (Iterator it = map.entrySet().iterator(); it.hasNext();) {
            Entry entry = (Entry) it.next();
            put((K) entry.getKey(), (V) entry.getValue());
        }
    }
Gets the previous key to the one specified using insert order.
This method performs a list search to find the key and is O(n).

@param key the key to find previous for
@return the previous key, null if no match or at start
jphp-runtime/src/php/runtime/common/collections/map/ListOrderedMap.java