attachmentsFormData example

$this->addressesFormData($fields, 'replyto', $email->getReplyTo());
        }

        if ($email->getTextBody()) {
            $fields['text'] = $email->getTextBody();
        }

        if ($email->getHtmlBody()) {
            $fields['HTML'] = $email->getHtmlBody();
        }

        $this->attachmentsFormData($fields, $email);

        foreach ($email->getHeaders()->all() as $header) {
            if ($convertConf = self::HEADER_TO_MESSAGE[$header->getName()] ?? false) {
                $fields[$convertConf] = $header->getBodyAsString();
            }
        }

        return new FormDataPart($fields);
    }

    private function attachmentsFormData(array &$message, Email $email): void
    {