Method set_boundary

examples/server/httplib.h:4014–4018

  MultipartFormDataParser() = default;

  void set_boundary(std::string &&boundary) {
    boundary_ = boundary;
    dash_boundary_crlf_ = dash_ + boundary_ + crlf_;
    crlf_dash_boundary_ = crlf_ + dash_ + boundary_;
  }

  bool is_valid() const { return is_valid_; }