Doctrine\ODM\PHPCR\Mapping\ClassMetadata::isSingleValuedAssociation PHP Method

    public function isSingleValuedAssociation($fieldName)
    {
        return isset($this->childMappings[$fieldName]) || $fieldName === $this->parentMapping || isset($this->referenceMappings[$fieldName]) && self::MANY_TO_ONE === $this->mappings[$fieldName]['type'];
    }