Context

I have a oneToMany relation between 2 entities. For example an Article which has many tags.

class Article
{
    private $id;
    private $name;
    private $tags;

    public function __construct()
    {
        $this->tags = new ArrayCollection();
    }
}

class Tag
{
    private $id;
    private $name;
}

My mapping is declared as XML.

Then, I want to get my tags ordered by name. For that, I have the following mapping in my Article:

<entity name="Article">
    <!-- ... -->
            <one-to-many field="tags" target-entity="Tag">
            <order-by>
                <order-by-field name="name"/>
            </order-by>
        </one-to-many>
</entity>

Problem

By default, this should sort my name field ASC (as mentionned in XSD file). However I have the exception Invalid order by orientation specified for Tag#name

Way of solution

For the moment, adding explicitly my direction attribute works fine but the default value isn't very default

<entity name="Article">
    <!-- ... -->
            <one-to-many field="tags" target-entity="Tag">
            <order-by>
                <order-by-field name="name" direction="ASC"/>
            </order-by>
        </one-to-many>
</entity>

I've investigate about it and it's appear that during the mapping reading (https://github.com/doctrine/doctrine2/blob/master/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php#L375), the default direction isn't set. Should be set it by default to this line ?