private boolean isSkipClass(final String className, final ClassLoader classLoader, final ClassLoadingChecker classLoadingChecker) {
        if (!isPluginPackage(className, classLoader)) {
            if (isDebug) {
                logger.debug("PluginFilter skip class:{}", className);
            }
            return true;
        }
        if (!classLoadingChecker.isFirstLoad(className)) {
            if (isDebug) {
                logger.debug("skip already loaded class:{}", className);
            }
            return true;
        }

        return false;
    }
@author Woonduk Kang(emeroad)
@author jaehong.kim
agent-module/profiler/src/main/java/com/navercorp/pinpoint/profiler/instrument/classloading/PlainClassLoaderHandler.java