GrantConfigurator only accepts custom grants implementing the League\Bundle\OAuth2ServerBundle\AuthorizationServer\GrantTypeInterface interface. However, if we want to use a custom grant from a library designed for league/oauth2-server and not for league/oauth2-server-bundle, we must create a new class inheriting from the library's grant in order to add the bundle interface.

It would be desirable for GrantConfigurator to also accept the basic league/oauth2-server interface.
In this case, to configure the access token TTL, I imagine it would be possible to use an attribute associated with the league.oauth2_server.authorization_server.grant tag.

What do you think about this?