@Override
    public V getValue() {
      return value;
    }
This class implements the cache entry manager with LRU policy.

@param <FK> The first key of cache value.
@param <SK> The second key of cache value.
@param <V> The cache value.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/analyze/cache/schema/dualkeycache/impl/LRUCacheEntryManager.java