public void test_clone() throws Exception {
Class.forName("com.alibaba.druid.proxy.DruidDriver");
DruidDriver driver = (DruidDriver) DriverManager.getDriver(url);
ConnectionProxyImpl connection = (ConnectionProxyImpl) driver.connect(url, new Properties());
connection.getRawObject();
FilterChain filterChain = (FilterChain) connection.createChain();
filterChain.cloneChain();