code: public function handle(GetResponseEvent $event)
      {
          $apiKey = $this->getApiKeyFromQueryOrHeader($event->getRequest());
  
          if (false === $apiKey) {
              return;
          }
  
          try {
              $token = $this->authenticationManager->authenticate(new ApiKeyToken($apiKey));
              $this->tokenStorage->setToken($token);
          } catch (AuthenticationException $failed) {
              $this->tokenStorage->setToken(null);
              $this->doFailureResponse($event);
          }
      }
docs: Handles API key authentication.
  
  @param GetResponseEvent $event A GetResponseEvent instance