@WebServlet("/http-connection-test")
public class HttpConnectionServlet extends HttpServlet {

    private static final String NON_EXISTENT_DOMAIN = "http://this-domain-does-not-exist-12345.invalid";

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        sendRequestToNonExistentDomain();
        out.write("success");
    }

    private void sendRequestToNonExistentDomain() throws HttpConnectionException {
        HttpURLConnection connection = null;
        
        try {
            URL url = new URL(NON_EXISTENT_DOMAIN);
            connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setConnectTimeout(5000);
            connection.setReadTimeout(5000);
            
            // Try to connect, this will throw an exception because the domain does not exist
            connection.connect();
            
            // Try to get the response code (will not actually reach here)
            int responseCode = connection.getResponseCode();
            System.out.println("Response Code: " + responseCode);
            
        } catch (IOException e) {
            // Catch the original exception and wrap it into HttpConnectionException
            // Save the HttpURLConnection instance as a field of the exception
            throw new HttpConnectionException(
                    "connect failed: " + NON_EXISTENT_DOMAIN,
                    e,
                    connection
            );
        }
    }
}

/**
 * Custom exception for wrapping HTTP connection related exceptions.
 * Contains an HttpURLConnection instance as a field.
 */
class HttpConnectionException extends RuntimeException {

  private final HttpURLConnection connection;

  public HttpConnectionException(String message, Throwable cause, HttpURLConnection connection) {
    super(message, cause);
    this.connection = connection;
  }

  public HttpConnectionException(String message, HttpURLConnection connection) {
    super(message);
    this.connection = connection;
  }

  /**
   * Get the associated HttpURLConnection instance.
   */
  public HttpURLConnection getConnection() {
    return connection;
  }
}

// everything is public since called directly from advice code
// (which is inlined into other packages)
public class HttpUrlState {

  private final WeakReference<Context> contextWeakReference;
  private boolean finished;
  // by default 0 is ignored
  private int statusCode = 0;

  public HttpUrlState(Context context) {
    this.contextWeakReference = new WeakReference<>(context);
  }

  public Context getContext() {
    return contextWeakReference.get();
  }
}