@Override
            public ClassicHttpResponse execute(final ClassicHttpRequest request,
                                               final HttpClientConnection conn,
                                               final HttpContext context) throws IOException, HttpException {
                requestExecutor.preProcess(request, httpProcessor, context);
                final ClassicHttpResponse response = requestExecutor.execute(request, conn, context);
                requestExecutor.postProcess(response, httpProcessor, context);
                return response;
            }
Tests for {@code PoolingHttpClientConnectionManager} that do require a server
to communicate with.
httpclient5-testing/src/test/java/org/apache/hc/client5/testing/sync/TestConnectionManagement.java