incorrect Free-Form Object on v6

[leppaott]

According to https://swagger.io/docs/specification/data-models/data-types/

A free-form object (arbitrary property/value pairs) is defined as:
type: object
This is equivalent to
type: object
additionalProperties: true
and
type: object
additionalProperties: {}

However for such a schema:
"data": { "type": "object", "additionalProperties": {} }

it is generated:

data?: { [key: string]: Record<string, never> | undefined; };

Record<string, never> is "empty object" but incorrect as free-form object.

If we change additionalProperties: true we get correct.

data?: { [key: string]: unknown | undefined; };