private void verifyOrigin(SessionContext context, HttpRequestMessage request, Origin primaryOrigin) {
        if (primaryOrigin == null) {
            String vip = context.getRouteVIP();
            // If no origin found then add specific error-cause metric tag, and throw an exception with 404 status.
            StatusCategoryUtils.setStatusCategory(
                    context,
                    ZuulStatusCategory.SUCCESS_LOCAL_NO_ROUTE,
                    "Unable to find an origin client matching `" + vip + "` to handle request");
            String causeName = "RESTCLIENT_NOTFOUND";
            originNotFound(context, causeName);
            ZuulException ze = new ZuulException(
                    "No origin found for request. name=" + vip + ", uri=" + request.reconstructURI(), causeName);
            ze.setStatusCode(404);
            throw ze;
        }
    }
Inject your own custom VIP based on your own processing
<p>
Note: this method gets called in the constructor so if overloading it or any methods called within, you cannot
rely on your own constructor parameters.

@return {@code null} if unused.
zuul-core/src/main/java/com/netflix/zuul/filters/endpoint/ProxyEndpoint.java