Doctrine simple_array returns one empty element instead of empty array

Question

I noticed that an entity field of type simple_array does not return the correct value for empty string.

Entity:

namespace MyBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * MyEntity
 *
 * @ORM\Entity(repositoryClass="MyBundle\Repository\MyEntityRepository")
 * @ORM\InheritanceType("SINGLE_TABLE")
 */
class MyEntity
{
    /**
     * @var string
     *
     * @ORM\Column(type="simple_array", nullable=true)
     */
    private $myList;
    
    /**
     * Get myList
     *
     * @return array
     */
    public function getMyList()
    {
        return $this->myList;
    }
}

Code:

$data = $em->getRepository("MyBundle:MyEntity")->find($recordId);

print_r($data->getMyList());

If myList in the database is an empty string (not NULL, already trimmed), why doctrine returns this:

Array
(
    [0] => 
)

instead of this?

Array
(
)

It act as I expect if the value is NULL but NULL and empty should be both evaluated as false, isn't true?

I'm using Symfony 2, there is a way to fix that?