@Override
public List<Artist> resolve(Long festivalId) {
    return queryDslHelper.select(artist)
        .from(festival)
        .join(stage).on(stage.festival.id.eq(festival.id))
        .join(stageArtist).on(stageArtist.stageId.eq(stage.id))
        .join(artist).on(artist.id.eq(stageArtist.artistId))
        .where(festival.id.eq(festivalId))
        .orderBy(artist.id.asc())
        .distinct()
        .fetch();
}