Symfony 4：Doctrine with manyToOne join

I trying Symfony 4 for "fun". And for that I try to rewrite an old website without framework as the moment, with Symfony 4.

For that I configure my app on my database with existing datas. And I'd make login form.

BUT on my User classe, I have some colomn who make me some issues.

See bellow my user's class's annotations:

/**
 * Utilisateur
 *
 * @ORM\Table(name="utilisateur", uniqueConstraints={@ORM\UniqueConstraint(name="mail", columns={"mail"})}, indexes={@ORM\Index(name="FK_UTILISATEUR_idDroit", columns={"idDroit"})})
 * @ORM\Entity
 */

and my user's struct :

idutilisateur
nom
prenom
mail
password
dateinscription
datevalidation
token
iddroit
plainPassword

Like you can see, I create before iddroit as foreign key of droit's table. Doctrine generated the propertie as

    /**
     * @var Droit
     *
     * @ORM\ManyToOne(targetEntity="Droit")
     * @ORM\JoinColumns({
     *   @ORM\JoinColumn(name="idDroit", referencedColumnName="idDroit")
     * })
     */
    private $iddroit;

And created the getter as

    public function getIddroit(): Droit
    {
        return $this->iddroit;
    }

And after followed the documentation about registration / login, the debugger respond =>

Return value of App\Entity\Utilisateur::getIddroit() must be an instance of App\Entity\Droit, null returned

So I imagine he want an object and not just an ID, even if in anotation it's making the Join rules. Any ID what's happened ?

And I understand to return an objet, but I have no idea how to return that.

If any suggestion.

Thanks guys ;)

Laurent