public function addClass(DocumentMetadata $metadata): void
    {
        $this->graph->addNode($metadata->name);

        $assocNames = $metadata->getAssociationNames();
        foreach ($assocNames as $assocName) {
            $targetClass = $metadata->getAssociationTargetClass($assocName);
            $this->graph->addNode($targetClass);
            $this->graph->connect($metadata->name, $targetClass);
        }
    }