泛化调用中
```java
public interface GenericService {

    Object $invoke(String method, String[] parameterTypes, Object[] args) throws GenericException;

}
```
这里可不可以异步调用返回个Future。我的工具实现会有多个 `ReferenceConfig` 缓存，我可以单独再用一个线程池来作为 `$invoke` 的执行上下文。但每个 `ReferenceConfig` 好像都有一组线程来维持，这个本身能不能异步调用？
*/
    private static final Protocol refprotocol = ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension();
    /**
     * The {@link Cluster}'s implementation with adaptive functionality, and actually it will get a {@link Cluster}'s
     * specific implementation who is wrapped with <b>MockClusterInvoker</b>
     */
    private static final Cluster cluster = ExtensionLoader.getExtensionLoader(Cluster.class).getAdaptiveExtension();
    /**
     * A {@link ProxyFactory} implementation that will generate a reference service's proxy,the JavassistProxyFactory is
     * its default implementation
     */
    private static final ProxyFactory proxyFactory = ExtensionLoader.getExtensionLoader(ProxyFactory.class).getAdaptiveExtension();
    /**
     * The url of the reference service
     */
    private final List<URL> urls = new ArrayList<URL>();
    /**
     * The interface name of the reference service
     */
    private String interfaceName;
    /**
     * The interface class of the reference service
     */
    private Class<?> interfaceClass;
    
    /**
     * client type
     */
    private String client;
    /**