/**
* Generates an attribute's key on base of its values
*
* @param ProductAttributeInterface $productAttribute
*
* @return string
*/
protected function generateProductAttributeKey(ProductAttributeInterface $productAttribute)
{
$values = [];
$productAttribute->getAttributeValues()->map(function (AttributeValueInterface $attributeValue) use(&$values) {
$values[$attributeValue->getId()] = $attributeValue->getId();
});
ksort($values);
return implode(',', $values);
}