[BUG] Generated API has no optional fields

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

Using the rest_framework_jwt module (i.e.) you get a serializer like this:

This get's generated in codegen to this:

The problem here is that token is still required on POST request, even though it shouldn't even be part of the POST request.

openapi-generator version

We are using "@openapitools/openapi-generator-cli": "^2.4.26", with "generator-cli": { "version": "5.2.0" } specified.

Generation Details

Code gets generated for Angular/ Typescript

Steps to reproduce

Use this yaml code to generate an API with the generator cli

"JSONWebToken": {
                "type": "object",
                "description": "Serializer class used to validate a username and password.\n\n'username' is identified by the custom UserModel.USERNAME_FIELD.\n\nReturns a JSON Web Token that can be used to authenticate later calls.",
                "properties": {
                    "password": {
                        "type": "string",
                        "writeOnly": true
                    },
                    "token": {
                        "type": "string",
                        "readOnly": true
                    },
                    "email": {
                        "type": "string",
                        "writeOnly": true
                    }
                },
                "required": [
                    "email",
                    "password",
                    "token"
                ]
            },

Related issues/PRs

Suggest a fix

To be honest, I am not even quite sure if this is a bug, so I can't suggest a fix. I think one solution could be to specify token as optional using the ? in TypeScript.

Start with the generator CLI and the supplied JSONWebToken YAML schema, then reproduce an Angular/TypeScript client and inspect how readOnly and required are represented in the generated model and POST request. Done means token is not required in the POST input while remaining available in responses, with generated output matching the schema.