final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final int maxPageSize = fessConfig.getPagingSearchPageMaxSizeAsInteger();
        final int configuredWindowSize = fessConfig.getRankFusionWindowSizeAsInteger();
        final int minimumWindowSize = maxPageSize * 2;

        if (configuredWindowSize < minimumWindowSize) {

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

    /**
     * Get the value for the key 'rank.fusion.rank_constant'. <br>
     * The value is, e.g. 20 <br>
     * comment: Rank constant for rank fusion.