message: Add ETag header for get contents.
diff: @@ -160,6 +160,8 @@ export class Controller {
  const data: ContentItem | undefined = await this.service.getContent(hashId);
  if (data) {
  res.contentType('application/octet-stream')
  + res.setHeader('ETag', hashId)
  + res.setHeader('Access-Control-Expose-Headers', '*')
  data.asStream().pipe(res)
  } else {
  res.status(404).send()
  