- [x] I have searched the [issues](https://github.com/apache/incubator-dubbo/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [FAQ](https://github.com/apache/incubator-dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 2.6.4

### Steps to reproduce this issue

1. GenericService泛化调用
2. 使用oninvoke、onreturn、onthrow
3. FutureFilter无法正常回调

### Expected Result
StaticContext.getKey(invoker.getUrl(), invocation.getMethodName(), Constants.ON_INVOKE_METHOD_KEY)
返回
com.alibaba.boot.dubbo.demo.consumer.DemoService:1.0.0.sayHello.oninvoke.method

### Actual Result
StaticContext.getKey(invoker.getUrl(), invocation.getMethodName(), Constants.ON_INVOKE_METHOD_KEY)
返回
com.alibaba.boot.dubbo.demo.consumer.DemoService:1.0.0.$invoke.oninvoke.method

预期是：

```
        String methodName = invocation.getMethodName();
        if("$invoke".equals(methodName)) {
            Object[] arguments = invocation.getArguments();
            methodName = (String) arguments[0];
        }
```

}
    public String getClient() {
        return client;
    }
    public void setClient(String client) {
        checkName("client", client);
        this.client = client;
    }
    @Parameter(excluded = true)
    public String getUrl() {
        return url;
    }
    public void setUrl(String url) {
        this.url = url;
    }
    public List<MethodConfig> getMethods() {
        return methods;
    }
    @SuppressWarnings("unchecked")
    public void setMethods(List<? extends MethodConfig> methods) {
        this.methods = (List<MethodConfig>) methods;
    }
    public ConsumerConfig getConsumer() {
        return consumer;
    }
    public void setConsumer(ConsumerConfig consumer) {
        ConfigManager.getInstance().addConsumer(consumer);
        this.consumer = consumer;
    }
    public String getProtocol() {