I'm trying to generate Java model with inheritance (Open API 2.0). The problem is similar to this one: How do you have the maven swagger codegen plugin generate Java classes using inheritance?

I want to achieve inheritance without discriminator attribute. Why this field has to be pointed in the parent class? Moreover according to docs:

The discriminator Fixed Field must reference a property from the same schema, and that it must be a required property

I DO NOT want to point any required fields. I just want to obtain inheritance. Is there any other way to do that? I know some "workaround" would be to change level of attributes:

"Child": {
  "allOf": [
    {"$ref": "#/components/schemas/Parent"},
  ],
  "properties": {.......}
}

But this is rather against the specs. Most surprising part is it works for openapi-generator-maven-plugin but in this time doesn't generate the correct code if we put "required" list. List of required fields will be omitted but inheritance will generate correctly.

Is there any other way to generate the proper inheritance without discriminator?