setUserLoader example

$passport = $event->getPassport();
        if (!$passport->hasBadge(UserBadge::class)) {
            return;
        }

        /** @var UserBadge $badge */
        $badge = $passport->getBadge(UserBadge::class);
        if (null !== $badge->getUserLoader()) {
            return;
        }

        $badge->setUserLoader($this->userProvider->loadUserByIdentifier(...));
    }
}

    public function authenticate(Request $request): Passport
    {
        $accessToken = $this->accessTokenExtractor->extractAccessToken($request);
        if (!$accessToken) {
            throw new BadCredentialsException('Invalid credentials.');
        }

        $userBadge = $this->accessTokenHandler->getUserBadgeFrom($accessToken);
        if ($this->userProvider && (null === $userBadge->getUserLoader() || $userBadge->getUserLoader() instanceof FallbackUserLoader)) {
            $userBadge->setUserLoader($this->userProvider->loadUserByIdentifier(...));
        }

        return new SelfValidatingPassport($userBadge);
    }

    public function createToken(Passport $passport, string $firewallName): TokenInterface
    {
        return new PostAuthenticationToken($passport->getUser(), $firewallName, $passport->getUser()->getRoles());
    }

    public function onAuthenticationSuccess(Request $request, TokenInterface $token, string $firewallName): ?Response
    {