question about generated .g.dart code

[programmerAbc]

I have following complex model

part 'A.g.dart';

@JsonSerializable()
class A{
  B b;
  C c;
  A();
}

@JsonSerializable()
class B{
  int v;
  B();
}

@JsonSerializable()
class C{
  int v;
  C();
}

When I use json_serializable to generate A.g.dart ,I got

part of 'A.dart';

// **************************************************************************
// JsonSerializableGenerator
// **************************************************************************

A _$AFromJson(Map<String, dynamic> json) {
  return A()
    ..b =
        json['b'] == null ? null : B.fromJson(json['b'] as Map<String, dynamic>)
    ..c = json['c'] == null
        ? null
        : C.fromJson(json['c'] as Map<String, dynamic>);
}

Map<String, dynamic> _$AToJson(A instance) => <String, dynamic>{
      'b': instance.b,
      'c': instance.c,
    };

B _$BFromJson(Map<String, dynamic> json) {
  return B()..v = json['v'] as int;
}

Map<String, dynamic> _$BToJson(B instance) => <String, dynamic>{
      'v': instance.v,
    };

C _$CFromJson(Map<String, dynamic> json) {
  return C()..v = json['v'] as int;
}

Map<String, dynamic> _$CToJson(C instance) => <String, dynamic>{
      'v': instance.v,
    };

everything is ok,but only one problem(maybe it is a problem just for me) is function _$AFromJson

A _$AFromJson(Map<String, dynamic> json) {
  return A()
    ..b =
        json['b'] == null ? null : B.fromJson(json['b'] as Map<String, dynamic>)
    ..c = json['c'] == null
        ? null
        : C.fromJson(json['c'] as Map<String, dynamic>);
}

it use B.fromJson and C.fromJson to decode json and create instance for member B and C in class A which makes me must implement fromJson method in both B and C, why not use _$BFromJson and _$CFromJson to decode json and create instrance for both of them? just like following code

A _$AFromJson(Map<String, dynamic> json) {
  return A()
    ..b =
        json['b'] == null ? null : _$BFromJson(json['b'] as Map<String, dynamic>)
    ..c = json['c'] == null
        ? null
        : _$CFromJson(json['c'] as Map<String, dynamic>);
}

and these implemention only need me implement fromJson method in class A , and I do not need to modify class B and class C any more which make my life better.

[kevmoo]

This package tries not to reason about how serialization is done with fields. It just looks for toJson and fromJson.

This eliminates a lot of special handling in the implementation.