toMap method Null safety

Implementation

@override
Map<String, Object?> toMap() {
  return {
    'date': this.date,
    'week': this.week,
    'lowestTemp': this.lowestTemp,
    'highestTemp': this.highestTemp,
    'windPowerDay': this.windPowerDay,
    'windPowerNight': this.windPowerNight,
    'windDirectionDay': this.windDirectionDay,
    'windDirectionrNight': this.windDirectionrNight,
    'phenomenonDay': this.phenomenonDay,
    'phenomenonNight': this.phenomenonNight,
    'airQualityIndex': this.airQualityIndex
  };
}