Exception logging in HttpAsyncClient callback

Question

How can I log exceptions which happen in an Apache HttpAsyncClient callback method? For example the following code throws NullPointerException, but it's hidden.

CloseableHttpAsyncClient client = HttpAsyncClients.createDefault();
try {
    final HttpGet request = new HttpGet("https://google.com");
    CountDownLatch sentRequestsCountDown = new CountDownLatch(1);
    String nullObject = null;
    final FutureCallback<HttpResponse> callback = new FutureCallback<HttpResponse>() {

        @Override
        public void completed(HttpResponse result) {
            sentRequestsCountDown.countDown();
            // NPE thrown here:
            String itThrowsNPE = nullObject.toString();
            System.out.println(itThrowsNPE);
        }

        @Override
        public void failed(Exception ex) {
            sentRequestsCountDown.countDown();
            System.out.println("failed");
        }

        @Override
        public void cancelled() {
            sentRequestsCountDown.countDown();
            System.out.println("cancelled");
        }
    };

    client.start();
    client.execute(request, callback);
    sentRequestsCountDown.await();
} finally {
    client.close();
}

When I run this, I don't see any exceptions logged. How can I configure a logger for this? It seems that NO_OP ExceptionLogger is used by default and I can't find a way to change it.