private static boolean hasClass(String className, ClassLoader classLoader) {
        try {
            Class.forName(className, false, classLoader);
            return true;
        } catch (ClassNotFoundException ignored) {
        }
        return false;
    }
@author Chaein Jung
@author jaehong.kim
agent-module/plugins/jetty/src/main/java/com/navercorp/pinpoint/plugin/jetty/JettyPlugin.java