SystemMessage.fromMap constructor Null safety

Implementation

factory SystemMessage.fromMap(Map<String, dynamic> param) {
  return SystemMessage(
    messageId: param["messageId"] as int?,
    type: SystemMessageTypeConverter().fromValue(param["type"] as String?),
    fromAccount: param["fromAccount"] as String?,
    targetId: param["targetId"] as String?,
    time: param["time"] as int?,
    status:
        SystemMessageStatusConverter().fromValue(param["status"] as String),
    content: param["content"] as String?,
    attach: param["attach"] as String?,
    unread: param["unread"] as bool?,
    customInfo: param["customInfo"] as String?,
  );
}