[Dart/Flutter]Add private fileds in Freezed data class

I want to add private fields in Freezed data class.

So, I tried to write this.

@freezed
class User with _$User {
  const factory User(
    String _id,
    String _name,
  ) = _User;
}

However, In my editor, displayed "Named parameters can't start with an underscore.(private_optional_parameter)" in user.freezed.dart

Please tell me what I solve this problem.