title: Set web server headers (Access-Control-Allow-Origin) in web-app running under jetty-runner
body: <p>I'm running the <a href="http://www.plantuml.com/server.html" rel="nofollow noreferrer">plantuml.war</a> on a server using <a href="http://www.eclipse.org/jetty/documentation/current/runner.html" rel="nofollow noreferrer">jetty-runner</a>. I need to enable the <code>Access-Control-Allow-Origin</code> header for CORS, but the way I found to do this points to a <a href="https://stackoverflow.com/questions/8303162/jetty-cross-origin-filter">web.xml</a> or an <a href="http://www.eclipse.org/jetty/documentation/current/override-web-xml.html" rel="nofollow noreferrer">override-web.xml</a>, which I think are out of my control because I'm using a third-party web-app in jetty-runner. I can't see a way to set this up in jetty.xml.</p>
  
  <p>Is there a way to enable the <code>Access-Control-Allow-Origin</code> header inside of jetty-runner?</p>