How to properly extend a Codeception module?

I am writing a custom Codeception module because I can't find how to achieve the same using the bundled Doctrine2 module. Basically I need to get the MAX value for a column. This is how the code looks like:

namespace Helper;

use Codeception\Module\Doctrine2;

class ExtendedDoctrine2 extends Doctrine2
{
    public function grabMaxValueFromRepository($entity, $field): array
    {
        $this->em->flush();
        $data = $this->em->getClassMetadata($entity);
        $qb   = $this->em->getRepository($entity)->createQueryBuilder('s');
        $qb->select('MAX(s.'.$field.')');
        $this->debug($qb->getDQL());

        return $qb->getQuery()->getSingleScalarResult();
    }
}

On my api.suite.yml I define the module as follow:

actor: ApiTester
modules:
    enabled:
        - Asserts
        - Symfony:
              app_path: 'src'
              environment: 'test'
        - Doctrine2:
            depends: Symfony
            cleanup: true
        - \Helper\ExtendedDoctrine2
            depends: Symfony
            cleanup: true

When I try to run the test I got the following error:

Module \Helper\ExtendedDoctrine2 depends: Symfony cleanup: true could not be found and loaded

What I am missing here? Is there any way to achieve get the MAX value without the need to write a module for this?

Codeception docs are not so good (no docs for how to extends modules) or at least is what seems to me, I read here and some links there leads to dead repositories on Github.