Method GetOrSetBackend

cpp/src/arrow/filesystem/s3fs.cc:2281–2287

  template <typename Error>
  S3Backend GetOrSetBackend(const Aws::Client::AWSError<Error>& error) {
    if (!backend_ || *backend_ == S3Backend::Other) {
      backend_ = DetectS3Backend(error);
    }
    DCHECK(backend_.has_value());
    return *backend_;
  }

  Result<S3Backend> GetBackend() {
    if (!backend_) {