} finally {
            // Cleanup
            if (originalValue != null) {
                System.setProperty("jcifs.smb.client.domain", originalValue);
            } else {
                System.clearProperty("jcifs.smb.client.domain");
            }
        }
    }

        // This test verifies that when the system property is null, the handler
        // falls back to using default handlers without throwing NullPointerException.
        System.clearProperty("java.protocol.handler.pkgs");
        setupMockProtocolHandlers();
        URL url = new URL("http://example.com/resource");

        URLConnection connection = handler.openConnection(url);