public NetworkClient.InFlightRequest completeLastSent(String node) {
        NetworkClient.InFlightRequest inFlightRequest = requestQueue(node).pollFirst();
        inFlightRequestCount.decrementAndGet();
        return inFlightRequest;
    }
@Test
    public void testCompleteLastSent() {
        int correlationId1 = addRequest(dest);
        int correlationId2 = addRequest(dest);
        assertEquals(2, inFlightRequests.count());

        assertEquals(correlationId2, inFlightRequests.completeLastSent(dest).header.correlationId());
        assertEquals(1, inFlightRequests.count());

        assertEquals(correlationId1, inFlightRequests.completeLastSent(dest).header.correlationId());
        assertEquals(0, inFlightRequests.count());
    }