public function validate($value, Constraint $constraint)
    {

        $bitlyProvider = new BitlyProvider(new GenericAccessTokenAuthenticator($value));
        $urlShortener = new UrlShortenerService($bitlyProvider);
        $link = new Link();
        $link->setLongUrl('http://www.campaignchain.com');

        try {
            $urlShortener->shorten($link);
        } catch (ExternalApiException $e) {
            $this->context->buildViolation($constraint->message)
                ->setParameter('%string%', $value)
                ->addViolation();
        } catch (\Exception $e) {
            // rethrow it
            throw $e;
        }


    }