protected function convertAggregateValues($attribute, array $values, AttributeConverterInterface $converter)
{
$this->aggregated[] = $attribute;
$converterName = $this->schema->getConverter($attribute);
$toAggregate = array_keys($this->schema->getConverterMap(), $converterName);
$values = $this->iterateAggregates($toAggregate, $values, $converter);
return is_array($values) ? $values : [$values];
}