code: func GenerateConnectionIDForInitial() (ConnectionID, error) {
  	r := make([]byte, 1)
  	if _, err := rand.Read(r); err != nil {
  		return nil, err
  	}
  	len := MinConnectionIDLenInitial + int(r[0])%(maxConnectionIDLen-MinConnectionIDLenInitial+1)
  	return GenerateConnectionID(len)
  }
docs: // GenerateConnectionIDForInitial generates a connection ID for the Initial packet.
  // It uses a length randomly chosen between 8 and 18 bytes.