code: public List<V> removeAll(K key) {
  		key = sanitizeKey(key);
  		List<V> removed = map.remove(key);
  		if (removed == null) {
  			return Collections.emptyList();
  		}
  
  		List<V> unmodifiableCopy = Collections.unmodifiableList(new ArrayList<V>(removed));
  		removed.clear();
  		return unmodifiableCopy;
  	}
docs: Removes all the values associated with a key
  @param key the key to remove
  @return the removed values or an empty list if the key doesn't exist
  (this list is immutable)