ReflectionException:
Class "Shopware\Core\Framework\MessageQueue\Handler\AbstractMessageHandler" not found while loading "Gshop\CustomGateway\Core\Checkout\Order\Message\OrderProcessHandler".

  at /www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/error-handler/DebugClassLoader.php:296
  at class_exists('Gshop\\CustomGateway\\Core\\Checkout\\Order\\Message\\OrderProcessHandler')
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/config/Resource/ClassExistenceResource.php:76)
  at Symfony\Component\Config\Resource\ClassExistenceResource->isFresh(0)
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/dependency-injection/ContainerBuilder.php:361)
  at Symfony\Component\DependencyInjection\ContainerBuilder->getReflectionClass('Gshop\\CustomGateway\\Core\\Checkout\\Order\\Message\\OrderProcessHandler')
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/messenger/DependencyInjection/MessengerPass.php:74)
  at Symfony\Component\Messenger\DependencyInjection\MessengerPass->registerHandlers(object(ContainerBuilder), array('messenger.bus.default'))
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/messenger/DependencyInjection/MessengerPass.php:58)
  at Symfony\Component\Messenger\DependencyInjection\MessengerPass->process(object(ContainerBuilder))
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/dependency-injection/Compiler/Compiler.php:80)
  at Symfony\Component\DependencyInjection\Compiler\Compiler->compile(object(ContainerBuilder))
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/dependency-injection/ContainerBuilder.php:767)
  at Symfony\Component\DependencyInjection\ContainerBuilder->compile()
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/http-kernel/Kernel.php:506)
  at Symfony\Component\HttpKernel\Kernel->initializeContainer()
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/shopware/core/Kernel.php:166)
  at Shopware\Core\Kernel->boot()
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/shopware/core/HttpKernel.php:115)
  at Shopware\Core\HttpKernel->doHandle(object(Request), 1, true)
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/shopware/core/HttpKernel.php:64)
  at Shopware\Core\HttpKernel->handle(object(Request), 1, true)
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/public/index.php:71)
  at Symfony\Component\HttpKernel\HttpKernelInterface@anonymous/www/htdocs/w01acc78/fm-test-shop-shopware6/public/index.php:61$0->handle(object(Request))
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/symfony/runtime/Runner/Symfony/HttpKernelRunner.php:35)
  at Symfony\Component\Runtime\Runner\Symfony\HttpKernelRunner->run()
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/autoload_runtime.php:29)
  at require_once('/www/htdocs/w01acc78/fm-test-shop-shopware6/vendor/autoload_runtime.php')
     (/www/htdocs/w01acc78/fm-test-shop-shopware6/public/index.php:14)