encode method
Implementation
@override
Future<MessagePayload> encode() async {
MessagePayload payload = await super.encode();
Map<String, dynamic> map = new Map();
map['o'] = operateUser;
map['g'] = groupId;
map['n'] = name;
payload.binaryContent = utf8.encode(json.encode(map)) as Uint8List?;
return payload;
}