Method ToString

cpp/src/arrow/ipc/message_internal_test.cc:122–126

  IpcWriteOptions options = {};

  std::string ToString() const {
    std::stringstream ss;
    ss << *this;
    return std::move(ss).str();
  }

  friend std::ostream& operator<<(std::ostream& os, const SampleMessageParams& p) {
    os << "legacy IPC = " << p.options.write_legacy_ipc_format << ", "