getOptInValidator example

    public function subscribe(RequestDataBag $dataBag, SalesChannelContext $context, bool $validateStorefrontUrl = true): NoContentResponse
    {
        $doubleOptInDomain = $this->systemConfigService->getString(
            'core.newsletter.doubleOptInDomain',
            $context->getSalesChannelId()
        );
        if ($doubleOptInDomain !== '') {
            $dataBag->set('storefrontUrl', $doubleOptInDomain);
            $validateStorefrontUrl = false;
        }

        $validator = $this->getOptInValidator($dataBag, $context, $validateStorefrontUrl);

        $this->validator->validate($dataBag->all(), $validator);

        if (($request = $this->requestStack->getMainRequest()) !== null && $request->getClientIp() !== null) {
            try {
                $this->rateLimiter->ensureAccepted(RateLimiter::NEWSLETTER_FORM, $request->getClientIp());
            } catch (RateLimitExceededException $e) {
                if (!Feature::isActive('v6.6.0.0')) {
                    throw $e;
                }