[BUG] Generates non-working code on versions 2.2.3+

[point-source]

Describe the bug
Starting in 2.2.3, some overrides are failing due to a type mismatch.

To Reproduce
Here is the swagger code: https://github.com/point-source/dart_plaid/blob/main/swagger/plaid_service.swagger
Error:

00:00 +0 -1: loading test/dart_plaid_test.dart [E]                                                                                                                                                                                                          
  Failed to load "test/dart_plaid_test.dart":
  lib/generated/plaid_service.swagger.dart:11776:43: Error: The return type of the method 'Transaction.transactionType' is 'TransactionTransactionType?', which does not match the return type, 'TransactionBaseTransactionType?', of the overridden method, 'TransactionBase.transactionType'.
   - 'TransactionTransactionType' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
   - 'TransactionBaseTransactionType' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
  Change to a subtype of 'TransactionBaseTransactionType?'.
    final enums.TransactionTransactionType? transactionType;
                                            ^
  lib/generated/plaid_service.swagger.dart:11560:47: Context: This is the overridden method ('transactionType').
    final enums.TransactionBaseTransactionType? transactionType;
                                                ^
  lib/generated/plaid_service.swagger.dart:24208:50: Error: The return type of the method 'AccountIdentity.verificationStatus' is 'AccountIdentityVerificationStatus?', which does not match the return type, 'AccountBaseVerificationStatus?', of the overridden method, 'AccountBase.verificationStatus'.
   - 'AccountIdentityVerificationStatus' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
   - 'AccountBaseVerificationStatus' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
  Change to a subtype of 'AccountBaseVerificationStatus?'.
    final enums.AccountIdentityVerificationStatus? verificationStatus;
                                                   ^
  lib/generated/plaid_service.swagger.dart:10958:46: Context: This is the overridden method ('verificationStatus').
    final enums.AccountBaseVerificationStatus? verificationStatus;
                                               ^
  lib/generated/plaid_service.swagger.dart:24330:48: Error: The return type of the method 'AccountAssets.verificationStatus' is 'AccountAssetsVerificationStatus?', which does not match the return type, 'AccountBaseVerificationStatus?', of the overridden method, 'AccountBase.verificationStatus'.
   - 'AccountAssetsVerificationStatus' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
   - 'AccountBaseVerificationStatus' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
  Change to a subtype of 'AccountBaseVerificationStatus?'.
    final enums.AccountAssetsVerificationStatus? verificationStatus;
                                                 ^
  lib/generated/plaid_service.swagger.dart:10958:46: Context: This is the overridden method ('verificationStatus').
    final enums.AccountBaseVerificationStatus? verificationStatus;
                                               ^
  lib/generated/plaid_service.swagger.dart:28946:54: Error: The return type of the method 'AssetReportTransaction.transactionType' is 'AssetReportTransactionTransactionType?', which does not match the return type, 'TransactionBaseTransactionType?', of the overridden method, 'TransactionBase.transactionType'.
   - 'AssetReportTransactionTransactionType' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
   - 'TransactionBaseTransactionType' is from 'package:dart_plaid/generated/plaid_service.enums.swagger.dart' ('lib/generated/plaid_service.enums.swagger.dart').
  Change to a subtype of 'TransactionBaseTransactionType?'.
    final enums.AssetReportTransactionTransactionType? transactionType;
                                                       ^
  lib/generated/plaid_service.swagger.dart:11560:47: Context: This is the overridden method ('transactionType').
    final enums.TransactionBaseTransactionType? transactionType;
                                                ^

Library version used:
2.2.3 up to 2.3.2

Additional context
Feel free to clone this repo, update the swagger library dependency, and regenerate to reproduce.

[fryette]

Yes, seems problem with the prefix enum.
For now, seems we should be able to drop it completely.(enum.)

New version will be released on Monday

[Vovanella95]

Hi @point-source
I was on VAC, will fix this issue soon.

[Vovanella95]

@point-source Fixed in latest version