* 启动provider

dubbo-demo-api-provider

* 启动consumer

dubbo-demo-api-consumer

consumer设置generic

```java
    public static void main(String[] args) {
        ReferenceConfig<DemoService> reference = new ReferenceConfig<>();
        reference.setApplication(new ApplicationConfig("dubbo-demo-api-consumer"));
        reference.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
        reference.setInterface(DemoService.class);
        reference.setGeneric(true);
        
        Object obj = reference.get();
        for(Class c : obj.getClass().getInterfaces()) {
            System.err.println(c);
        }
        DemoService service = reference.get();
        String message = service.sayHello("dubbo");
        System.out.println(message);
    }
```

客户端会报错：

```
Exception in thread "main" java.lang.ClassCastException: org.apache.dubbo.common.bytecode.proxy0 cannot be cast to org.apache.dubbo.demo.DemoService
	at org.apache.dubbo.demo.consumer.Application.main(Application.java:42)
```
if (ref == null) {
            return;
        }
        if (destroyed) {
            return;
        }
        destroyed = true;
        try {
            invoker.destroy();
        } catch (Throwable t) {
            logger.warn("Unexpected error occured when destroy invoker of ReferenceConfig(" + url + ").", t);
        }
        invoker = null;
        ref = null;
        // 
        dispatch(new ReferenceConfigDestroyedEvent(this));
    }
    public synchronized void init() {
        if (initialized) {
            return;
        }
        if (bootstrap == null) {
            bootstrap = DubboBootstrap.getInstance();
            bootstrap.init();
        }
        checkAndUpdateSubConfigs();
        checkStubAndLocal(interfaceClass);
        ConfigValidationUtils.checkMock(interfaceClass, this);
        Map<String, String> map = new HashMap<String, String>();
        map.put(SIDE_KEY, CONSUMER_SIDE);