### Environment

* Dubbo version: 3.0
StaticDirectory.destroy方法最后要对列表做clear操作，但是ReferenceConfig的createInvokerForLocal构造StaticDirectory传入的列表类型是Collections.singletonList，执行clear就会抛异常：
```
[08/10/21 07:35:39:302 UTC] main  WARN config.ReferenceConfig:  [DUBBO] Unexpected error occurred when destroy invoker of ReferenceConfig(null)., dubbo version: 3.0.4-SNAPSHOT, current host: 172.19.112.1
java.lang.UnsupportedOperationException
	at java.util.AbstractList.remove(AbstractList.java:161)
	at java.util.AbstractList$Itr.remove(AbstractList.java:374)
	at java.util.AbstractList.removeRange(AbstractList.java:571)
	at java.util.AbstractList.clear(AbstractList.java:234)
	at org.apache.dubbo.rpc.cluster.directory.StaticDirectory.destroy(StaticDirectory.java:91)
	at org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker.destroy(AbstractClusterInvoker.java:113)
	at org.apache.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.destroy(MockClusterInvoker.java:79)
	at org.apache.dubbo.config.ReferenceConfig.destroy(ReferenceConfig.java:219)
```
URL url = URL.valueOf(u);
                if (StringUtils.isEmpty(url.getPath())) {
                    url = url.setPath(interfaceName);
                }
                url = url.setScopeModel(getScopeModel());
                url = url.setServiceModel(consumerModel);
                if (UrlUtils.isRegistry(url)) {
                    urls.add(url.putAttribute(REFER_KEY, referenceParameters));
                } else {
                    URL peerUrl = getScopeModel().getApplicationModel().getBeanFactory().getBean(ClusterUtils.class).mergeUrl(url, referenceParameters);
                    peerUrl = peerUrl.putAttribute(PEER_KEY, true);
                    urls.add(peerUrl);
                }
            }
        }
    }
    /**
     * Get URLs from the registry and aggregate them.
     */
    private void aggregateUrlFromRegistry(Map<String, String> referenceParameters) {
        checkRegistry();
        List<URL> us = ConfigValidationUtils.loadRegistries(this, false);
        if (CollectionUtils.isNotEmpty(us)) {
            for (URL u : us) {
                URL monitorUrl = ConfigValidationUtils.loadMonitor(this, u);
                if (monitorUrl != null) {
                    u = u.putAttribute(MONITOR_KEY, monitorUrl);
                }
                u = u.setScopeModel(getScopeModel());
                u = u.setServiceModel(consumerModel);