encode method Null safety

Implementation

Object encode() {
  final Map<Object?, Object?> pigeonMap = <Object?, Object?>{};
  pigeonMap['accessToken'] = accessToken;
  pigeonMap['baseURL'] = baseURL;
  pigeonMap['dataPath'] = dataPath;
  pigeonMap['assetPath'] = assetPath;
  pigeonMap['tileStoreUsageMode'] = tileStoreUsageMode?.index;
  return pigeonMap;
}