static Map<String, TtlTransformlet> childClassLoaderFirstMergeTransformlets(
            Map<ClassLoader, Map<String, TtlTransformlet>> classLoader2Transformlet, ClassLoader classLoader
    ) {
        Map<String, TtlTransformlet> ret = new HashMap<>();

        final ArrayDeque<ClassLoader> chain = new ArrayDeque<>();
        chain.add(classLoader);
        while (classLoader.getParent() != null) {
            classLoader = classLoader.getParent();

            chain.addFirst(classLoader);
        }

        for (ClassLoader loader : chain) {
            final Map<String, TtlTransformlet> m = classLoader2Transformlet.get(loader);
            if (m == null) continue;

            ret.putAll(m);
        }

        return ret;
    }
@author Jerry Lee (oldratlee at gmail dot com)
ttl-agent/src/main/java/com/alibaba/ttl3/agent/TtlExtensionTransformletManager.java