[BUG] Generating models with enum discriminator

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The model for an object with an enum discriminator generates a constructor that causes a compilation error. Related issue in swagger-codegen: https://github.com/swagger-api/swagger-codegen/issues/10441
For Enum type discriminator, a constructor is being generated that assigns a string to the enum discriminator. For example:
public ExternalKeySpecDetails() { this.ekmType = this.getClass().getSimpleName(); }

openapi-generator version

4.0.1

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Related issues/PRs

https://github.com/swagger-api/swagger-codegen/issues/10441

Suggest a fix

It doesn't seem the constructor is used anywhere. Can we just get rid of it during the generation?

Start by reproducing the issue from the inline OpenAPI declaration with an enum discriminator and inspect the generated Java model constructor shown in the report. Confirm the generated model fails to compile because a string is assigned to the enum; done means generation no longer produces that invalid assignment and the resulting model compiles.