jetty-overlay-deployer/src/test/resources/home/overlays/instances/myfoo=green/WEB-INF/web-overlay.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app 
   xmlns="http://java.sun.com/xml/ns/javaee" 
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
   version="2.5"> 

  <display-name>Green Test WebApp</display-name>
  
  <context-param>
    <param-name>overlay</param-name>
    <param-value>instances/myfoo=green/web.xml</param-value>
  </context-param>
  <context-param>
    <param-name>instance</param-name>
    <param-value>instances/myfoo=green/web.xml</param-value>
  </context-param>
  
</web-app>