[REQ] Feature Request Description

When we generate a typescript client, openapi generator makes interfaces to describe types. In other languages like java it generates pojo-s.

If anybody reuses these generated interfaces/classes it is a disadvantage, that generated code definition allows to modify the object after creating it.

So I need a feature (that can be a parameter) to make generated model immutable.

In typescript for instance if you use this parameter, it would generate an immutable model:

export interface Balance { 
    /**
     * Amount
     */
    readonly amount: number;
    /**
     * ISO 4217 Alpha 3 currency code
     */
    readonly currency?: Balance.CurrencyEnum;
}

It is also possible to make immutable model in other languages like kotlin, java, etc.

The issue names OpenAPI Generator and TypeScript interfaces, with Java and Kotlin as additional examples, but no files, tests, or entry points. Start by locating the generators and configuration path for model generation; done means an option produces immutable models across the intended languages, including readonly TypeScript properties.