presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/cache/CachingHiveMetastore.java/CachingHiveMetastore/WithIdentity
class CachingHiveMetastore:        public WithIdentity(HiveIdentity identity, T key)
        {
            this.identity = requireNonNull(identity, "identity is null");
            this.key = requireNonNull(key, "key is null");
            this.hashCode = Objects.hash(identity, key);
        }