### 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)
```
if ("false".equals(retryValue)) {
                        map.put(methodConfig.getName() + ".retries", "0");
                    }
                }
            }
        }
        return map;
    }
    @SuppressWarnings({"unchecked"})
    private T createProxy(Map<String, String> referenceParameters) {
        if (shouldJvmRefer(referenceParameters)) {
            createInvokerForLocal(referenceParameters);
        } else {
            urls.clear();
            if (url != null && url.length() > 0) {
                // 
                parseUrl(referenceParameters);
            } else {
                // 
                if (!LOCAL_PROTOCOL.equalsIgnoreCase(getProtocol())) {
                    aggregateUrlFromRegistry(referenceParameters);
                }
            }
            createInvokerForRemote();
        }
        if (logger.isInfoEnabled()) {
            logger.info("Referred dubbo service " + interfaceClass.getName());
        }
        URL consumerUrl = new ServiceConfigURL(CONSUMER_PROTOCOL, referenceParameters.get(REGISTER_IP_KEY), 0,
            referenceParameters.get(INTERFACE_KEY), referenceParameters);