toMap method
转换成可以序列化的map
Implementation
Map<String, dynamic> toMap() {
final Map<String, dynamic> updateMap = <String, dynamic>{};
void addIfNonNull(String fieldName, dynamic value) {
if (value != null) {
updateMap[fieldName] = value;
}
}
addIfNonNull('polygonsToAdd', serializeOverlaySet(polygonsToAdd!));
addIfNonNull('polygonsToChange', serializeOverlaySet(polygonsToChange!));
addIfNonNull('polygonIdsToRemove', polygonIdsToRemove?.toList());
return updateMap;
}