code: protected function getFiles(MessageInterface $message)
      {
          if (!($message instanceof AttachmentsAwareInterface)) {
              return [];
          }
  
          // Process files
          list($attachments, $inline) = $this->processAttachments($message->getAttachments());
  
          // Format params
          $files = [];
          if ($attachments) {
              $files['attachment'] = $attachments;
          }
          if ($inline) {
              $files['inline'] = $inline;
          }
  
          return $files;
      }
docs: {@inheritdoc}