Sharing singleton objects between embedded Jetty (Spring context) and non-web application

I am building a Spring MVC app on an embedded(an existing application runs it) Jetty server to build a restful API. The problem is the existing application is a non-web app which has multiple singleton objects. I could not figure out how to share the singleton objects between the existing application context and the newly created Spring MVC context (AnnotationConfigApplicationContext). Transforming the existing app to a web app and making a war file is not an option at the moment. Do you have any suggestions to solve this problem? Thank you