@Override
    public void putAll(Map<? extends K, ? extends V> m) {
        for (Entry<? extends K, ? extends V> entry : m.entrySet()) {
            put(entry.getKey(), entry.getValue());
        }
    }
two-way map, you can get key by value, or get value by key.

@author <a href=mailto:zhanggeng.zg@antfin.com>GengZhang</a>
core/common/src/main/java/com/alipay/sofa/rpc/common/struct/TwoWayMap.java