[BUG] Arrays of unspecified subtype default to non-nullable "Object"

[point-source]

Describe the bug
When generating code for a model with an array property which does not specify its subtype, the generated type is List<Object> which excludes null. Here is an example of a model definition:

      "MyModel": {
        "title": "MyModel",
        "type": "object",
        "properties": {
          "Rows": {
            "type": "array",
            "items": {
              "type": "array",
              "items": { }
            },
            "nullable": true
          }
        }
      }

here is the code that gets generated:

*.swagger.dart:

  @JsonKey(name: 'Rows', includeIfNull: false, defaultValue: <List<Object>>[])
  final List<List<Object>>? rows;

*.swagger.g.dart:

      rows: (json['Rows'] as List<dynamic>?)
              ?.map(
                  (e) => (e as List<dynamic>).map((e) => e as Object).toList())
              .toList() ??
          [],

To Reproduce
Please attach swagger and code snippet of generated value

Expected behavior
Since the api spec does not specify the subtype, it should probably be either dynamic or Object? like so:

*.swagger.dart:

  @JsonKey(name: 'Rows', includeIfNull: false, defaultValue: <List<Object?>>[])
  final List<List<Object?>>? rows;

*.swagger.g.dart:

      rows: (json['Rows'] as List<dynamic>?)
              ?.map(
                  (e) => (e as List<dynamic>).map((e) => e as Object?).toList())
              .toList() ??
          [],

OR

*.swagger.dart:

  @JsonKey(name: 'Rows', includeIfNull: false, defaultValue: <List<dynamic>>[])
  final List<List<dynamic>>? rows;

*.swagger.g.dart:

      rows: (json['Rows'] as List<dynamic>?)
              ?.map(
                  (e) => (e as List<dynamic>).toList())
              .toList() ??
          [],

Swagger specification link
See model example above

Library version used:
2.8.5

[Vovanella95]

@point-source make sense