SaslStartCommand constructor
      
      SaslStartCommand(
    
    
- Db db,
- String mechanism,
- Uint8List payload, {
- SaslStartOptions? saslStartOptions,
- Map<String, Object> ? rawOptions,
- Connection? connection,
Implementation
SaslStartCommand(Db db, String mechanism, Uint8List payload,
    {SaslStartOptions? saslStartOptions,
    Map<String, Object>? rawOptions,
    Connection? connection})
    : super(
          db, <String, Object>{...?saslStartOptions?.options, ...?rawOptions},
          command: <String, Object>{
            keySaslStart: 1,
            keyMechanism: mechanism,
            keyPayload: base64.encode(payload)
          },
          connection: connection);