### 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)
```
return ref;
    }
    @Override
    public synchronized void destroy() {
        super.destroy();
        if (destroyed) {
            return;
        }
        destroyed = true;
        try {
            if (invoker != null) {
                invoker.destroy();
            }
        } catch (Throwable t) {
            logger.warn("Unexpected error occurred when destroy invoker of ReferenceConfig(" + url + ").", t);
        }
        invoker = null;
        ref = null;
        if (consumerModel != null) {
            ModuleServiceRepository repository = getScopeModel().getServiceRepository();
            repository.unregisterConsumer(consumerModel);
        }
        getScopeModel().getConfigManager().removeConfig(this);
    }
    protected synchronized void init() {
        if (initialized) {
            return;
        }
        if (getScopeModel() == null) {
            setScopeModel(ApplicationModel.defaultModel().getDefaultModule());