code: @Test public void test_getAdaptiveExtension_protocolKey() throws Exception {
    UseProtocolKeyExt ext=ExtensionLoader.getExtensionLoader(UseProtocolKeyExt.class).getAdaptiveExtension();
  {
      String echo=ext.echo(URL.valueOf("1.2.3.4:20880"),"s");
      assertEquals("Ext3Impl1-echo",echo);
      Map<String,String> map=new HashMap<String,String>();
      URL url=new URL("impl3","1.2.3.4",1010,"path1",map);
      echo=ext.echo(url,"s");
      assertEquals("Ext3Impl3-echo",echo);
      url=url.addParameter("key1","impl2");
      echo=ext.echo(url,"s");
      assertEquals("Ext3Impl2-echo",echo);
    }
  {
      Map<String,String> map=new HashMap<String,String>();
      URL url=new URL(null,"1.2.3.4",1010,"path1",map);
      String yell=ext.yell(url,"s");
      assertEquals("Ext3Impl1-yell",yell);
      url=url.addParameter("key2","impl2");
      yell=ext.yell(url,"s");
      assertEquals("Ext3Impl2-yell",yell);
      url=url.setProtocol("impl3");
      yell=ext.yell(url,"d");
      assertEquals("Ext3Impl3-yell",yell);
    }
  }
  