EventSubscriber.php

<?php

namespace Drupal\module_install_class_loader_test1;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Defines an event subscriber that conditionally unsets the event list.
 *
 * @see Drupal\module_install_class_loader_test2\EventSubscriber
 * @see Drupal\Tests\system\Functional\Module\ClassLoaderTest::testMultipleModules()
 */
class EventSubscriber implements EventSubscriberInterface {
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        $events = [];
        // If the autoloader is not fixed during module install when the modules
        // module_install_class_loader_test1 and module_install_class_loader_test2
        // are enabled in the same request the class_exists() will cause a crash.
        // This is because \Composer\Autoload\ClassLoader maintains a negative
        // cache.
        if (class_exists('\\Drupal\\module_install_class_loader_test2\\EventSubscriber')) {
            $events = [];
        }
        return $events;
    }

}