### 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)
```
*/
    private Map<String, AsyncMethodInfo> createAsyncMethodInfo() {
        Map<String, AsyncMethodInfo> attributes = null;
        if (CollectionUtils.isNotEmpty(getMethods())) {
            attributes = new HashMap<>(16);
            for (MethodConfig methodConfig : getMethods()) {
                AsyncMethodInfo asyncMethodInfo = methodConfig.convertMethodConfig2AsyncInfo();
                if (asyncMethodInfo != null) {
                    attributes.put(methodConfig.getName(), asyncMethodInfo);
                }
            }
        }
        return attributes;
    }
    /**
     * Append all configuration required for service reference.
     *
     * @return reference parameters
     */
    private Map<String, String> appendConfig() {
        Map<String, String> map = new HashMap<>(16);
        map.put(INTERFACE_KEY, interfaceName);
        map.put(SIDE_KEY, CONSUMER_SIDE);
        ReferenceConfigBase.appendRuntimeParameters(map);
        if (!ProtocolUtils.isGeneric(generic)) {
            String revision = Version.getVersion(interfaceClass, version);
            if (revision != null && revision.length() > 0) {
                map.put(REVISION_KEY, revision);
            }
            String[] methods = methods(interfaceClass);