Optional fields incorrect on object types, expected null fields

[cdaringe]

openapi-typescript version

7.0.2

Node.js version

22

OS + version

15.8

Description

Problem

OpenAPI defines types observed over the wire, but the generated optional types do not match. Specifically, optional types are defined as optional in typescript, versus null

Reproduction

1. Define a schema: Demo: { type: "object", properties: { foo: { ... }, bar: { ... } }
2. Generate typescript:
   3. actual: { Demo: { foo?: number, bar?: number }

Expected result

{ Demo: { foo: number | null, bar: number | null }

I expected null

Required

• My OpenAPI schema is valid and passes the Redocly validator (npx @redocly/cli@latest lint)

Extra

• I’m willing to open a PR (see CONTRIBUTING.md)

[Guuz]

Same bug happening here. The types are a union:

Device: components["schemas"]["DeviceBase"] & {
            status: "DISCONNECTED";
            propertyOverwrite: null;
        };

DeviceBase also has propertyOverwrite as a boolean for instance. Before 0.17 this correctly worked, but after 0.17 propertyOverwrite just gets removed entirely from the object and we get compiler errors due to it.