encode method Null safety

Implementation

Object encode() {
  final Map<Object?, Object?> pigeonMap = <Object?, Object?>{};
  pigeonMap['position'] = position?.index;
  pigeonMap['marginLeft'] = marginLeft;
  pigeonMap['marginTop'] = marginTop;
  pigeonMap['marginRight'] = marginRight;
  pigeonMap['marginBottom'] = marginBottom;
  return pigeonMap;
}