toMap method Null safety

Implementation

@override
Map<String, Object?> toMap() {
  return {
    'suggestAddrResult': this.suggestAddrResult?.toMap(),
    'routes': this.routes?.map((e) => e.toMap()).toList(),
    'totalRoutes': this.totalRoutes,
    'taxiInfo': this.taxiInfo?.toMap(),
    'origin': this.origin?.toMap(),
    'destination': this.destination?.toMap()
  };
}