private function addConfigAssociations(ClassMetadata $metadata, $className)
    {
        foreach ($metadata->getAssociationNames() as $association) {
            if (!$metadata->isAssociationInverseSide($association)
                && $metadata->isSingleValuedAssociation($association)) {
                $this->configs[$className][1][$association] = $metadata->getAssociationTargetClass($association);
            }
        }
    }