Fatal error: Uncaught Error: Class 'JMS\Serializer\Metadata\ClassMetadata' not found in /var/www/html/vendor/jms/serializer/tests/Metadata/Driver/php/Discriminator.ObjectWithXmlAttributeDiscriminatorParent.php:5 Stack trace: #0 {main} thrown in /var/www/html/vendor/jms/serializer/tests/Metadata/Driver/php/Discriminator.ObjectWithXmlAttributeDiscriminatorParent.php on line 5