[typescript] allOf fails with chained inheritance

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?

Description

Using openapigenerator 6.0.1, with generator "typescript".

If a spec uses allOf to specify an inheritance chain, the child in the inheritance chain will have its own properties and the properties of its most distant parent, but not the properties of its closest parent.

In the provided example, the instance of class Child would have Child.ChildAttribute and Child.GrandparentAttribute but not Child.ParentAttribute.

openapi-generator version

6.0.1

OpenAPI declaration file content or url

https://gist.github.com/MattiasMartens/49415a0fe5c3922500424d61c5a3c97a

Related issues/PRs

First raised in https://github.com/OpenAPITools/openapi-generator/issues/927.

Start by reproducing the chained allOf case from the provided OpenAPI declaration with the typescript generator, comparing the generated Child class with its parent classes. Trace how the generator resolves inherited properties; done means Child includes its own, parent, and grandparent attributes.