Somewhat obscure builder configuration causes error

[skuwamoto]

graph.add('bool-changeOwnerOfCollection', changeOwnerOfCollection, ['db', 'owner', '!collectionSlug'])
    .builds('!bool-addCollectionRef')
      .using('!requiredVariants.is_super_user', {userId: 'args.owner.id'}, 'collectionId-fromSlug', {rel: 'shared.constants.CollectionRelationships.OWNED'})

Causes an error that says that "node requiredVariants not found"