encode method Null safety

Implementation

Object encode() {
  final Map<Object?, Object?> pigeonMap = <Object?, Object?>{};
  pigeonMap['id'] = id;
  pigeonMap['geometry'] = geometry;
  pigeonMap['fillSortKey'] = fillSortKey;
  pigeonMap['fillColor'] = fillColor;
  pigeonMap['fillOpacity'] = fillOpacity;
  pigeonMap['fillOutlineColor'] = fillOutlineColor;
  pigeonMap['fillPattern'] = fillPattern;
  return pigeonMap;
}