public static <K, V> boolean removeAllHelper(Map<K, V> map, Collection<?> collection) {
        int oldSize = map.size();
        Iterator<?> it = collection.iterator();
        while (it.hasNext()) {
            map.remove(it.next());
        }
        return oldSize != map.size();
    }
Helper for writing standard Java collection interfaces to a data
structure like {@link ArrayMap}.

@author RePlugin Team
replugin-host-library/replugin-host-lib/src/main/java/com/qihoo360/replugin/utils/basic/MapCollections.java