public static ClassLoader getClassLoader(String appConnName, Supplier<ClassLoader> createClassLoader) {
        if(!CLASS_LOADER_MAP.containsKey(appConnName)) {
            synchronized (AppStandardClassUtils.class) {
                if(!CLASS_LOADER_MAP.containsKey(appConnName)) {
                    CLASS_LOADER_MAP.put(appConnName, createClassLoader.get());
                    LOGGER.info("Has stored {} ClassLoader.", CLASS_LOADER_MAP.size());
                }
            }
        }
        return CLASS_LOADER_MAP.get(appConnName);
    }
This class is defined for AppConn jar, if some classes in AppConn want to load a class in AppConn jar.
dss-standard/dss-standard-common/src/main/java/com/webank/wedatasphere/dss/standard/common/utils/AppStandardClassUtils.java