private static void closeAndDrain(HttpResponseWriter actualRes, HttpResponse deferredRes) {
        actualRes.close();
        deferredRes.subscribe(NoopSubscriber.get());
        deferredRes.whenComplete().join();
        waitForEventLoop();
    }
Closes the response returned by the delegate and consumes everything from it, so that its close future
is completed.
core/src/test/java/com/linecorp/armeria/client/limit/ConcurrencyLimitingClientTest.java