swagger-core annotations required to specify HTTP requestBody form parameters?

As mentioned in my reply to your other question, swagger-core 2.x reader targets JAX-RS and its implementations: a typical APPLICATION_FORM_URLENCODED endpoint would be implemented e.g. in Jersey like this one processed as this test 

However your approach is almost right (using @RequestBody with @Content and @Schema) but adding schema properties via annotation is not (yet) supported. You have 2 options

1. create a class representing your schema with properties, and use that in the `implementation` field, like:

class Test00020RequestBody {

  public String Test00020;

}

@Path("/Test00020")

  public class Test00020 extends HttpServlet {

  

          @Override

          @POST

          @Operation (

                  summary = "Ask something, get something back.",

                  requestBody = @RequestBody( description = "Form POST parameters in request body", required = true,

                          content = @Content( schema = @Schema(implementation =Test00020RequestBody.class))))

          @Consumes(MediaType.APPLICATION_FORM_URLENCODED)

          @Produces(MediaType.TEXT_HTML)

          public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ...

or use a filter  to programmatically define exactly what you need