Cannot create a simple redirect in my own custom module

Hi,

I want to create a simple redirect for anonymous users in my module. For this I've used the example in the article at https://drupalize.me/blog/201502/responding-events-drupal-8. This article describes a redirect by an "event subscriber service". My redirect should happen based on the user id. The event subscriber service is recognized by Drupal 8. Because my debugger (XDebug) steps into my code.

The problem is, if I'm requesting any URL with an anonymous user, the browser messages me after a while: "Too many redirects".

It follows the code, which I had programmed so far.

OwnNotes.services.yml:

services:
    ownnotes.subscriber:
        class: Drupal\OwnNotes\LoginStateSubscriber
        tags:

          - {name: event_subscriber}

src/LoginStateSubscriber.php (the redirect is defined in the "checkForRedirection" method:

// Declare the namespace that our event subscriber is in. This should follow the
// PSR-4 standard, and use the EventSubscriber sub-namespace.
namespace Drupal\OwnNotes;

// This is the interface we are going to implement.
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
// This class contains the event we want to subscribe to.
use Symfony\Component\HttpKernel\KernelEvents;

use \Drupal\Core\Routing\TrustedRedirectResponse;

/**
 * Subscribe to KernelEvents::REQUEST events and redirect to the login form if an anonymous user
 * is requesting the site.
 */
class LoginStateSubscriber implements EventSubscriberInterface {
  /**
   * {@inheritdoc}
   */
  static function getSubscribedEvents() {
    $events[KernelEvents::REQUEST][] = array('checkForRedirection');
    return $events;
  }

  /**
   * This method is called whenever the KernelEvents::REQUEST event is
   * dispatched.
   *
   * @param GetResponseEvent $event
   */
  public function checkForRedirection(\Symfony\Component\HttpKernel\Event\GetResponseEvent $event) {
    if (intval(\Drupal::currentUser()->getAccount()->id()) == 0 &&
      $_SERVER['REQUEST_URI'] !== '/user/login') {

      $event->setResponse(new TrustedRedirectResponse('/user/login'));

      /**
       * Tried also:
       * $event->setResponse(new RedirectResponse('http://example.com/'));
       */

    }
  }
}

Additionally I need to restart the Apache webserver to see any changes on the code taking effect. A cache-rebuild with Drush isn't enough. Does anybody know why?

I think there "must" be an elegant way to create a simple redirect in Drupal 8.

Thanks in advance to your help!