Better idiom for listing inner items of a 1-to-N-to-1 relationship?

I have the following model:

1 RepositoryDTO can have many ResourceDTOs, and in each ResourceDTO is exacly one TeamDTO.

So to get the TeamDTOs from the RepositoryDTO, I am doing the following:

RepositoryDTO repoDTO = ...
List<TeamDTO> teamsLinkedToRepo = getTeamsLinkedTo(repoDTO);

private List<TeamDTO> getTeamsLinkedTo(final RepositoryDTO repository) {
    final List<TeamDTO> teamsLinkedToRepository = new ArrayList<TeamDTO>();
    for (final ResourceDTO resourceDTO : repository.getResources()) {
      teamsLinkedToRepository.add(resourceDTO.getTeam());
    }
    return teamsLinkedToRepository;
}

I'm just wondering is there a better idiom for doing this, maybe using Google Guava?