static AccessPredicate fullyAuthenticated() {
        return (a, c) -> !(a instanceof AnonymousAuthenticationToken);
    }
All authenticated users can access the protected instance excluding anonymous users.

@return A newly created AccessPredicate that checks whether the user is explicitly authenticated.
grpc-server-spring-boot-starter/src/main/java/net/devh/boot/grpc/server/security/check/AccessPredicate.java