Autowiring services based on the types they implement is deprecated since Symfony 3.3 and won't be supported in version 4.0. You should rename (or alias) the "fp_openid.identity_manager" service to "Fp\OpenIdBundle\Model\IdentityManagerInterface" instead.
Fix for symfony 3.3 deprecation message:
Autowiring services based on the types they implement is deprecated since Symfony 3.3 and won't be supported in version 4.0. You should rename (or alias) the "fp_openid.identity_manager" service to "Fp\OpenIdBundle\Model\IdentityManagerInterface" instead.