If I understand well, instead of doing this:

```php
    /**
     * @var MyNamespace\Role
     * @ODM\ReferenceMany(targetDocument="MyNamespace\Role")
     */
    protected $roles = array();
```

I should do:

```php
    /**
     * @var MyNamespace\Role
     * @ODM\ReferenceMany(targetDocument="MyNamespace\Role")
     */
    protected $roles;

    /**
     * Initializes the roles variable.
     */
    public function __construct()
    {
        $this->roles = new ArrayCollection();
    }
```

Right?