code: @Test public void canceledAfterResponseIsDeliveredDoesNothing() throws Exception {
    server.enqueue(new MockResponse().setBody("A"));
    server.play();
    final CountDownLatch latch=new CountDownLatch(1);
    final AtomicReference<String> bodyRef=new AtomicReference<String>();
    Request request=new Request.Builder().url(server.getUrl("/a")).tag("request A").build();
    client.enqueue(request,new Response.Receiver(){
      @Override public void onFailure(    Failure failure){
        throw new AssertionError();
      }
      @Override public boolean onResponse(    Response response) throws IOException {
        client.cancel("request A");
        bodyRef.set(response.body().string());
        latch.countDown();
        return true;
      }
    }
  );
    latch.await();
    assertEquals("A",bodyRef.get());
  }
  