getMediaUrls example

    public function serialize(Config $config, EntityDefinition $definition, $entity): iterable
    {
        if ($entity instanceof Struct) {
            $entity = $entity->jsonSerialize();
        }

        yield from parent::serialize($config, $definition, $entity);

        if (isset($entity['media'])) {
            yield 'media' => implode('|', $this->getMediaUrls($entity));
        }

        if (!isset($entity['visibilities'])) {
            return;
        }

        $visibilities = $entity['visibilities'];
        if ($visibilities instanceof Struct) {
            $visibilities = $visibilities->jsonSerialize();
        }

        

'template' => $template,
                    'exception' => (string) $e,
                ], $templateData)
            );

            return null;
        }
        if (isset($data['testMode']) && (bool) $data['testMode'] === true) {
            $this->templateRenderer->disableTestMode();
        }

        $mediaUrls = $this->getMediaUrls($data, $context);

        $binAttachments = $data['binAttachments'] ?? null;

        $mail = $this->mailFactory->create(
            $data['subject'],
            [$senderEmail => $data['senderName']],
            $recipients,
            $contents,
            $mediaUrls,
            $data,
            $binAttachments
        );