}
        fessConfig = ComponentUtil.getFessConfig();
        cache = CacheBuilder.newBuilder()
                .maximumSize(fessConfig.getSuggestPopularWordCacheSizeAsInteger().longValue())
                .expireAfterWrite(fessConfig.getSuggestPopularWordCacheExpireAsInteger().longValue(), TimeUnit.MINUTES)
                .build();
    }

    /**

     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     * @throws NumberFormatException When the property is not integer.
     */
    Integer getSuggestPopularWordCacheSizeAsInteger();

    /**
     * Get the value for the key 'suggest.popular.word.cache.expire'. <br>
     * The value is, e.g. 60 <br>
     * comment: Cache expiration (seconds) for popular word suggestion.