code: public List<V> replace(K key, V value) {
  		List<V> replaced = removeAll(key);
  		if (value != null) {
  			put(key, value);
  		}
  		return replaced;
  	}
docs: Replaces all values with the given value.
  @param key the key
  @param value the value with which to replace all existing values, or null
  to remove all values
  @return the values that were replaced (this list is immutable)