Updated Drupal to 8.6. This goes with the following updates because it's possible...

[yaffs-website] / vendor / symfony / dependency-injection / Tests / Fixtures / Container / ConstructorWithMandatoryArgumentsContainer.php

<?php

namespace Symfony\Component\DependencyInjection\Tests\Fixtures\Container;

class ConstructorWithMandatoryArgumentsContainer
{
    public function __construct($mandatoryArgument)
    {
    }
}