toJson method Null safety

Implementation

Map<String, dynamic> toJson() {
  final Map<String, dynamic> data = new Map<String, dynamic>();
  data['appId'] = this.appId;
  data['bizId'] = this.bizId;
  data['mode'] = this.mode;
  data['videoWidth'] = this.videoWidth;
  data['videoHeight'] = this.videoHeight;
  data['videoBitrate'] = this.videoBitrate;
  data['videoFramerate'] = this.videoFramerate;
  data['videoGOP'] = this.videoGOP;
  data['backgroundColor'] = this.backgroundColor;
  data['backgroundImage'] = this.backgroundImage;
  data['audioSampleRate'] = this.audioSampleRate;
  data['audioBitrate'] = this.audioBitrate;
  data['audioChannels'] = this.audioChannels;
  data['mixUsers'] = this.mixUsers;
  data['streamId'] = this.streamId;
  return data;
}