given that is in resources you would need to some coding anyway.
I would suggest writing undertow ServletExtension http://undertow.io/undertow-docs/undertow-docs-1.3.0/index.html#servlet-extensions
where you can register handler that will serve files from your resource, all you need to do is create ResourceHandler and pass him ResourceManager http://undertow.io/javadoc/1.3.x/io/undertow/server/handlers/resource/ResourceManager.html
There are already quite few implementations including ClassPathResourceManager that could probably work for what you want, in other case just override #getResource method with your own impl and that is.
Thank you. Had to do some tinkering but the approach worked out.