toMap method Null safety

Implementation

Map<String, dynamic> toMap() => <String, dynamic>{
      "keyword": keyword,
      "fromTime": fromTime,
      "toTime": toTime,
      "sessionLimit": sessionLimit,
      "msgLimit": msgLimit,
      "asc": asc,
      "p2pList": p2pList,
      "teamList": teamList,
      "senderList": senderList,
      "msgTypeList": msgTypeList
          ?.map((e) => NIMMessageTypeConverter(messageType: e).toValue())
          .toList(),
      "msgSubtypeList": msgSubtypeList,
    };