public final int valuesForKey(@NotNull K key) {
    Object current = myMap.get(key);
    if (current == null) {
      return 0;
    }
    else if (current instanceof ValueList) {
      //noinspection unchecked
      return ((ValueList<V>)current).size();
    }
    return 1;
  }
public final int valuesForKey(@NotNull K key)