Why is lein ring uberwar not including main manifest attribute - clojure

Question

when I invoke java -jar my-application.war
after using lein ring uberware
I receive a response of no main manifest attribute, in my-app.war
here is my code:
the namespace below provides the :gen-class and -main function which are needed:
(ns nutrif.core
(:require [ring.middleware.params]
[ring.middleware.resource :refer [wrap-resource]]
[ring.adapter.jetty]
[clojure.java.io :as io])
(:gen-class))
(defn handler [request]
{:status 200
:header {"Content-Type" "text/html"}
:body (io/input-stream (io/resource "public/index.html"))})
(def app
(wrap-resource handler "public"))
(defn -main
[& [port]]
(let [port (Integer. (or port
(System/getenv "PORT")
8080))]
(ring.adapter.jetty/run-jetty #'app {:port port
:join? false})))
Here is the my project.clj which points to the namespace with the -main function. What am I missing ?
(defproject nutrif "0.1.0-SNAPSHOT"
:description "FIXME: write description"
:url "http://example.com/FIXME"
:license {:name "Eclipse Public License"
:url "http://www.eclipse.org/legal/epl-v10.html"}
:dependencies [[org.clojure/clojure "1.6.0"]
[ring "1.3.0"]
[ring/ring-jetty-adapter "1.3.0"]]
:plugins [[lein-ring "0.8.11"]]
:dev-dependencies [[ring-serve "0.1.2"]
[javax.servlet/servlet-api "2.5"]]
:ring {:handler nutrif.core/app
:resource-paths [resources public]}
:main nutrif.core
:aot [nutrif.core])