@NotNull
  @Override
  public OrderRootsEnumerator roots(@NotNull NotNullFunction<? super OrderEntry, ? extends OrderRootType> rootTypeProvider) {
    return new OrderRootsEnumeratorImpl(this, rootTypeProvider);
  }
@NotNull
  @Override
  public OrderRootsEnumerator roots(@NotNull NotNullFunction<? super OrderEntry, ? extends OrderRootType> rootTypeProvider)