[BUG] [JAVA] [Micronaut] - Using inheritance results in superclass having all fields from subclasses

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

When using inheritance (discriminator), the generated subclasses gains fields in their constructors for other subclasses fields. Also, the superclass, gets all the fields of all the subclasses combined. Some getters are also duplicated resulting in compile errors.

It seems all the fields are merged together.

openapi-generator version

6.11.0

OpenAPI declaration file content or url

https://gist.github.com/KangoV/ad36a85420f7c8187a208e09fe9d4242

Generation Details

Using Micronaut Gradle plugin:

    openapi {
        version = "6.11.0"
        server(file(layout.buildDirectory.file("tmp/$specFile"))) {
            apiPackageName = basePackage + ".api"
            modelPackageName = basePackage + ".api.model"
            useOptional = true
            useReactive = false
        }
    }

Generates the superclass/subclass:

https://gist.github.com/KangoV/8a62886376207e281e8b0fedd008a24d

Start with the OpenAPI declaration gist and the Micronaut Gradle plugin configuration, then compare the generated superclass and subclasses in the linked output gist. Reproduce generation with version 6.11.0 and verify that each class contains only its own and inherited fields, with no duplicated getters or compile errors.