[REQ][Dart] Generator adds unnecessary null handling for non-nullable primitive responses

Description:
The Dart generator adds unnecessary null handling code for non-nullable primitive responses, making the return type nullable when it shouldn't be.
Is there an option to prevent this behavior?

Current behavior:

Future<bool?> hasUnreadNotification() async {
  final response = await hasUnreadNotificationWithHttpInfo();
  if (response.statusCode >= HttpStatus.badRequest) {
    throw ApiException(response.statusCode, await _decodeBodyBytes(response));
  }
  // When a remote server returns no body with a status of 204, we shall not decode it.
  // At the time of writing this, `dart:convert` will throw an "Unexpected end of input"
  // FormatException when trying to decode an empty string.
  if (response.body.isNotEmpty && response.statusCode != HttpStatus.noContent) {
    return await apiClient.deserializeAsync(await _decodeBodyBytes(response), 'bool',) as bool;
  }
  return null;
}

Expected behavior:

Future<bool> hasUnreadNotification() async {
  final response = await hasUnreadNotificationWithHttpInfo();
  if (response.statusCode >= HttpStatus.badRequest) {
    throw ApiException(response.statusCode, await _decodeBodyBytes(response));
  }
  return await apiClient.deserializeAsync(await _decodeBodyBytes(response), 'bool',) as bool;
}

Backend endpoint:

@GetMapping("/has-unread-notification")
fun hasUnreadNotification(): Boolean {
    return dashboardService.hasUnreadNotification()
}

Version:

• OpenAPI Generator: 7.10.0
• Dart SDK: 3.24.3

Additional context:
The backend endpoint always returns a non-nullable boolean, but the generator adds unnecessary null handling code and makes the return type nullable.

Start by reproducing the generated Dart client for the shown non-nullable Boolean endpoint and inspect how the Dart generator handles primitive responses. Done means the generated method returns Future, avoids unnecessary null handling for a 204 or empty body, and preserves the expected deserialization behavior.