Doctrine integration

Hello,
Very interested by this solution, so i tried it. 
But Doctrine version is higher and code exposed here does not work anymore.
So i picked code for App\Libraries\doctrine.php in doctrine "installation and configuration" page (didn't kept

Code:

require_once "vendor/autoload.php";

line)

PHP Code:

namespace App\Libraries;

use Doctrine\DBAL\DriverManager;
use Doctrine\ORM\EntityManager;
use Doctrine\ORM\ORMSetup;

use CodeIgniter\Config\BaseConfig;
use Config\Database as DbConfig;

class Doctrine
{
    public $entityManager;
    public function __construct()
    {        
        $dbConfig = config(DbConfig::class);
        $dbParams = [
            'driver'  => strtolower($dbConfig->default['DBDriver']),
            'user'    => $dbConfig->default['username'],
            'password' => $dbConfig->default['password'],
            'dbname'  => $dbConfig->default['database'],
            'host'    => $dbConfig->default['hostname'],
        ];        
        $config = ORMSetup::createAttributeMetadataConfiguration(
            paths: array(__DIR__."/../app/Models/Entities"),
            isDevMode: true,
        );
        $connection = DriverManager::getConnection($dbParams, $config);      
        $entityManager = new EntityManager($connection, $config);
    }
} 


Kept Service.php like exposed here.
No error messages but, in home.php controller

PHP Code:

        $entityManager = service('doctrine');
        d($entityManager); 


displays NULL
Can someone help ?
Will tatter/relations be modified to comply to the requirements of v4.5.1 version?
Thanks
Eric