code: @Test public void varyMatchesChangedRequestHeaderField() throws Exception {
    server.enqueue(new MockResponse().addHeader("Cache-Control: max-age=60").addHeader("Vary: Accept-Language").setBody("A"));
    server.enqueue(new MockResponse().setBody("B"));
    server.play();
    URL url=server.getUrl("/");
    HttpURLConnection frConnection=openConnection(url);
    frConnection.addRequestProperty("Accept-Language","fr-CA");
    assertEquals("A",readAscii(frConnection));
    HttpURLConnection enConnection=openConnection(url);
    enConnection.addRequestProperty("Accept-Language","en-US");
    assertEquals("B",readAscii(enConnection));
  }
  