EventListener/LoadORMMetadataSubscriber.php
protected function getClass($key)
    {
        if ($this->container->hasParameter($key)) {
            return $this->container->getParameter($key);
        }

        if (class_exists($key)) {
            return $key;
        }

        throw new \InvalidArgumentException(
            sprintf('The class %s does not exists.', $key)
        );
    }
protected function getClass($key)
    {
        if ($this->container->hasParameter($key)) {
            return $this->container->getParameter($key);
        }

        if (class_exists($key)) {
            return $key;
        }

        throw new \InvalidArgumentException(
            sprintf('The class %s does not exists.', $key)
        );
    }
@param string           $key

@return string
@throws \InvalidArgumentException