@Override
    public InputStream getResourceAsStream(ClassLoader targetClassLoader, String internalName) {
        try {
            if (targetClassLoader == null) {
                ClassLoader classLoader = ClassLoader.getSystemClassLoader();
                if (classLoader == null) {
                    return null;
                }
                appendToBootstrapClassLoaderSearch();
                return classLoader.getResourceAsStream(internalName);
            }
        } catch (Exception e) {
            logger.warn("Failed to load plugin resource as stream {} with classLoader", internalName, e);
            return null;
        }
        logger.warn("Invalid bootstrap class loader. cl={}", targetClassLoader);
        return null;
    }
@author Woonduk Kang(emeroad)
@author jaehong.kim
agent-module/profiler/src/main/java/com/navercorp/pinpoint/profiler/instrument/classloading/BootstrapClassLoaderHandler.java