public Class findClass(String keyString) {
        for (int i = 0; i < buckets.length; i++) {
            Entry bucket = buckets[i];

            if (bucket == null) {
                continue;
            }

            for (Entry<K, V> entry = bucket; entry != null; entry = entry.next) {
                Object key = bucket.key;
                if (key instanceof Class) {
                    Class clazz = ((Class) key);
                    String className = clazz.getName();
                    if (className.equals(keyString)) {
                        return clazz;
                    }
                }
            }
        }

        return null;
    }
for concurrent IdentityHashMap

@author wenshao[szujobs@hotmail.com]
src/main/java/com/alibaba/fastjson/util/IdentityHashMap.java