# Background

In our schema, we frequently do something like the following:

{
  "type": "object",
  "required": [
    "user"
  ],
  "properties": {
    "user": {
      "nullable": false,
      "allOf": [
        {
          "$ref": "#/components/schemas/User"
        }
      ]
    }
  }
}

In the above example, the user property needs to be nullable, but the schema of the property is actually a reference to a non-nullable component. The semi-official (but not ideal) way that was established to handle this case is to nest the $ref in an allOf/anyOf/oneOf array and mark it as nullable (you can't have other annotations alongside $ref).

While this approach works in our Android code generator, and our server-side validator, it produces unexpected results in CreateAPI when using isInliningPropertiesFromReferencedSchemas because CreateAPI will attempt to inline the allOf as a new type instead of referencing the actual type as an optional property.

Changes

To reproduce the issue locally, I first needed to setup some test coverage since we hadn't tested it before now. To do that, I've added a new inlining.yml schema and setup a few scenarios that test this behaviour in general.

Finally, I applied the actual fix in 48237df