[BUG] Inheritance and Maps canno coexist

Created by: maxper75

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?

Description

The attached file represents an inheritance containing, in the subclass, a hashmap with a custom type. Well, I don't get this, but I get different results. As a result I'd expect to get

public class SubObjectDTO extends SuperObjectDTO {
private Map<String, MapElementDTO> additionalMap;
....[getters and setter and whatever more]---
}
public class SuperObjectDTO {
private UUID id;
private String superProperty1;
private String superProperty2;
....[getters and setter and whatever more]---
}

public class MapElementDTO {
private int property1;
private boolean property2;
private String property3;
....[getters and setter and whatever more]---
}

while I get the Super class and the map element ok, the subclass varies depending from the inclusion of the clause of allOf. If I add this, I see the element with the properties of the superclass, but no additionalProperties. If i remove this, I dont get the super class props but just the additional ones. Is this a bug or I'm doing a mistake?

openapi-generator version

openapi-generator version 4.2.2

OpenAPI declaration file content or url

See attached gist https://gist.github.com/maxper75/62a7cdac09037679641c56f552bc21ef#file-buggy-openapi-inheritance-map-json

Command line used for generation

openapi-generator generate -g spring -i model.json -o prova

Steps to reproduce

just launch the command :D