Generated copyWith() for nested lists doesn't keep its inner child values

[daniel-webstep]

Describe the bug
When creating models that contains nested lists, the code generation for copyWith() doesn't keep track of the inner child. Instead, an empty list is returned. The toJson() works as expected.

To Reproduce
Steps to reproduce the behavior:

1. Create a class like

class: NestedLists
fields:
  doubleValue: double
  listDouble: List<double>
  listListDouble: List<List<double>>

2. run serverpod generate
3. Create the following tests

import 'dart:convert';

import 'package:example_server/src/generated/protocol.dart';
import 'package:test/test.dart';

void main() {
  NestedLists baseObject() {
    return NestedLists(doubleValue: 0, listDouble: [
      1
    ], listListDouble: [
      [2]
    ]);
  }

  group('NestedLists', () {
    test('toJson() returns a valid json for nested lists.', () {
      var obj = baseObject();
      var expectedJson = jsonDecode(
          '{"doubleValue": 0.0, "listDouble": [1.0], "listListDouble": [[2.0]]}');
      expect(obj.toJson(), equals(jsonDecode(expectedJson)));
    });
    test('copyWith() does return the same values.', () {
      var obj = baseObject();
      var expectedObj = baseObject();
      expect(obj.copyWith(), expectedObj);
    });
  });
}

4. Run the tests
5. See error

Expected behavior

Expected: _NestedListsImpl:<{"doubleValue":0.0,"listDouble":[1.0],"listListDouble":[[2.0]]}>
  Actual: _NestedListsImpl:<{"doubleValue":0.0,"listDouble":[1.0],"listListDouble":[]}>

package:matcher                                          expect
package:example_server/src/test/nested_lists_test.dart 25:7  main.<fn>.<fn>

Serverpod versions

• CLI Version: Serverpod version: 1.2.6
• Library version: serverpod: 1.2.6

Platform information
Ubuntu 22.04.4 LTS through Docker.

[Isakdl]

Thank you for the detailed report!

[bfemmer]

I'll pick this one up to work on (I don't see a linked PR ... if anyone is already working this one, please let me know).