### Environment

* Dubbo version: 2.7.6-SNAPSHOT
* Operating System version: Mac
* Java version: 1.8

### Steps to reproduce this issue

run dubbo-samples-simplified-registry-xml 

org.apache.dubbo.samples.simplified.registry.xml.DemoServiceIT
### Expected Result

should pass

### Actual Result

throw exception
} else {
                        enabled = url.getParameter(ENABLED_KEY, true);
                    }
                    if (enabled) {
                        invoker = new InvokerDelegate<>(protocol.refer(serviceType, url), url, providerUrl);
                    }
                } catch (Throwable t) {
                    logger.error("Failed to refer invoker for interface:" + serviceType + ",url:(" + url + ")" + t.getMessage(), t);
                }
                if (invoker != null) { 
                    newUrlInvokerMap.put(key, invoker);
                }
            } else {
                newUrlInvokerMap.put(key, invoker);
            }
        }
        keys.clear();
        return newUrlInvokerMap;
    }
    /**
     * Merge url parameters. the order is: override > -D >Consumer > Provider
     *
     * @param providerUrl
     * @return
     */
    private URL mergeUrl(URL providerUrl) {
        providerUrl = ClusterUtils.mergeUrl(providerUrl, queryMap); 
        providerUrl = overrideWithConfigurator(providerUrl);
        providerUrl = providerUrl.addParameter(Constants.CHECK_KEY, String.valueOf(false));