encode method
Implementation
@override
Future<MessagePayload> encode() async {
MessagePayload payload = await super.encode();
Map<String, dynamic> map = <String, dynamic>{};
map['o'] = creator;
map['g'] = groupId;
map['n'] = groupName;
payload.binaryContent = Uint8List.fromList(json.encode(map).codeUnits);
return payload;
}