public V remove(K key) {
        if (ref != null) {
            Map<K, V> map = ref.get();
            if (map != null) {
                return map.remove(key);
            }
        }
        return null;
    }
Removes a value from cache.
@param key the cache entry key
@return the cache entry value
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/properties/SoftCache.java