MorphOne relation

[goeil]

Hello friends,

I'm trying to set up a relation in my repository.
A subscription has a recipient field, which can be either a person or an institution (2 differents repositories/tables).
I've set up correct fields and methods with morphing in my Laravel Models (used to it).

But what shall I put in the 2nd argument of my make function, because by definition a morphic does not know the type by advance?

public static function related(): array {

    return [

        'recipient' => \Binaryk\LaravelRestify\Fields\MorphOne::make(

                                        'recipient', PersonRepository::class)
    ];
}

PersonRepository::class OR InstitutionRepository::class
Repository::class ? (does not work)

This is not in the official documentation. BelongsTo and MorphOne are considered as synonymes (also in the source code), and I don't know how to advance.

Thanks all