class ConcurrentHashMultimap implements Multimap<K, V> {

    @Override
    public Collection<V> removeAll(@Nullable Object key) {
        if (key == null) {
            return Collections.emptyList();
        }
        return Collections.unmodifiableCollection(entries.remove(key).values());
    }

    public  ConcurrentHashMultimap(ValueIdentityExtractor<V> valueIdentityExtractor, ConflictResolver<V> conflictResolver);

}