sp-dev-fx-webparts/samples/react-aad-webapi/api/pnp.api.contosoorders/App_Start/WebApiConfig.cs

using System.Web.Http;

namespace pnp.api.contosoorders {
    public static class WebApiConfig {
        public static void Register(HttpConfiguration config) {
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        }
    }
}