Object schema generated for Unit Kotlin type

[orange-buffalo]

Describe the bug

With upgrade from 2.6.0 to 2.7.0 we experience unexpected changes to generated schema - Unit Kotlin return type appears in the schema.

To Reproduce

Consider Spring REST Controller method like this:

    @PostMapping("{token}/activate")
    @ResponseStatus(HttpStatus.NO_CONTENT)
    suspend fun activateUser(
        @PathVariable token: String,
        @RequestBody @Valid request: UserActivationRequestDto
    ) {
 ...

In 2.6.0, the schema was generated correctly, in our opinion:

  /api/user-activation-tokens/{token}/activate:
    post:
      ...
      responses:
        "204":
          description: No Content

In 2.7.0, however, the extra type is generated:

  /api/user-activation-tokens/{token}/activate:
    post:
     ...
      responses:
        "204":
          description: No Content
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Unit"
...
components:
  schemas:
    Unit:
      type: object

Additional context
As a side note, we are using OpenApiGenerator to generate TypeScript client from the OpenAPI schema, and now the client code has method return types object instead of previous void.

[dineshkj13]

Yes this could break the client in other languages too, client would expect null response but now it expects {} which is not there in the response