// ## Arrange ##
        final HeaderRecordingMockHttpURLConnection[] mockHolder = new HeaderRecordingMockHttpURLConnection[1];
        CurlRequest req = new OpenOverrideCurlRequest(Curl.Method.GET, "http://dummy", u -> {
            HeaderRecordingMockHttpURLConnection mock = new HeaderRecordingMockHttpURLConnection(u);
            mockHolder[0] = mock;
            return mock;
        });