Surely you wanted to use the OpenAPI Specification (OAS) JSON you used for your spec class on the iris-web-swagger-ui iris package. The generated OAS from the ##class(%REST.API).GetWebRESTApplication(...) method is very crude, with no description on the parameters or the expected response structure.

So after creating your REST application from an OAS you should have:

• A generated application.disp.cls class
• An application.spec.cls class (we'll add a path to the OpenAPI spec that's residing in the "XData OpenAPI" property)
• An application.impl.cls class (we'll just implement the GetSpec method)