code: @Test public void wrappedHandlers() throws Exception {
    JettyEmbeddedServletContainerFactory factory=getFactory();
    factory.setServerCustomizers(Arrays.asList(new JettyServerCustomizer(){
      @Override public void customize(    Server server){
        Handler handler=server.getHandler();
        HandlerWrapper wrapper=new HandlerWrapper();
        wrapper.setHandler(handler);
        HandlerCollection collection=new HandlerCollection();
        collection.addHandler(wrapper);
        server.setHandler(collection);
      }
    }
  ));
    this.container=factory.getEmbeddedServletContainer(exampleServletRegistration());
    this.container.start();
    assertThat(getResponse(getLocalUrl("/hello")),equalTo("Hello World"));
  }
  