onboard method
Returns true
if authentication is successful for the existing atsign in device.
Implementation
Future<bool> onboard() async {
var atClientServiceInstance = _getClientServiceForAtsign(_atsign)!;
var result = await atClientServiceInstance.onboard(
atClientPreference: _atClientPreference, atsign: _atsign);
if (_atsign == null) {
_atsign = await this.getAtSign();
}
atClientServiceMap.putIfAbsent(_atsign, () => atClientServiceInstance);
await _sync();
return result;
}