### 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)
```
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package org.apache.dubbo.config;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.Version;
import org.apache.dubbo.common.constants.RegistryConstants;
import org.apache.dubbo.common.extension.ExtensionLoader;
import org.apache.dubbo.common.logger.Logger;
import org.apache.dubbo.common.logger.LoggerFactory;
import org.apache.dubbo.common.url.component.ServiceConfigURL;
import org.apache.dubbo.common.utils.CollectionUtils;
import org.apache.dubbo.common.utils.ConfigUtils;