code: private boolean isProxied(HttpServletRequest httpServletRequest) {
          if (Proxy.isProxyClass(httpServletRequest.getClass())) {
              InvocationHandler handler = Proxy.getInvocationHandler(httpServletRequest);
              return handler instanceof ServletRequestInvocationHandler;
          }
          return false;
      }
docs: Check if this request is already proxied by pax wicket
  
  @param httpServletRequest
  @return true if the instance is a proxy and invocationhandler is a {@link ServletRequestInvocationHandler}