getMailAttachmentsConfig example

$attachmentsConfig = new MailAttachmentsConfig(
            Context::createDefaultContext(),
            new MailTemplateEntity(),
            new MailSendSubscriberConfig(false),
            [],
            Uuid::randomHex()
        );

        $mail->setMailAttachmentsConfig($attachmentsConfig);

        static::assertEquals($attachmentsConfig, $mail->getMailAttachmentsConfig());
    }
}

        foreach ($message->getAttachmentUrls() as $url) {
            try {
                $mimeType = $this->filesystem->mimeType($url);
            } catch (UnableToRetrieveMetadata) {
                $mimeType = null;
            }
            $message->attach($this->filesystem->read($url) ?: '', basename($url), $mimeType);
        }

        $config = $message->getMailAttachmentsConfig();

        if (!$config) {
            return $this->decorated->send($message, $envelope);
        }

        $attachments = $this->attachmentsBuilder->buildAttachments(
            $config->getContext(),
            $config->getMailTemplate(),
            $config->getExtension(),
            $config->getEventConfig(),
            $config->getOrderId()
        );