I have a `Customer` entity with fields such as FirstName, LastName.

Also I have a method in the entity like this:

```
public function getFullName() {
        return sprintf("%s %s", $this->getLastName(), $this->getFirstName());
}

```

My `configureListFields` function looks like the following:

```
protected function configureListFields(ListMapper $listMapper)
{
    $listMapper
        ->add('fullName')
        ->add('birthday')
        ->add('email')
        ->add('phone')
    ;
}

```

How can I make the field **fullName** sortable?

How can I add custom sort criteria with or without Doctrine ORM?