code: @Test public void testGenericInvokeWithRpcContext(){
    RpcContext.getContext().setAttachment("myContext","123");
    HessianServiceImpl server=new HessianServiceImpl();
    ProxyFactory proxyFactory=ExtensionLoader.getExtensionLoader(ProxyFactory.class).getAdaptiveExtension();
    Protocol protocol=ExtensionLoader.getExtensionLoader(Protocol.class).getAdaptiveExtension();
    URL url=URL.valueOf("hessian://127.0.0.1:5342/" + HessianService.class.getName() + "?version=1.0.0");
    Exporter<HessianService> exporter=protocol.export(proxyFactory.getInvoker(server,HessianService.class,url));
    Invoker<GenericService> invoker=protocol.refer(GenericService.class,url);
    GenericService client=proxyFactory.getProxy(invoker,true);
    String result=(String)client.$invoke("context",new String[]{"java.lang.String"},new Object[]{"haha"});
    Assert.assertEquals("Hello, haha context, 123",result);
    invoker.destroy();
    exporter.unexport();
  }
  