final InnerHitBuilder innerHitBuilder = new InnerHitBuilder().setName(fessConfig.getQueryCollapseInnerHitsName())
                    .setSize(fessConfig.getQueryCollapseInnerHitsSizeAsInteger());
            fessConfig.getQueryCollapseInnerHitsSortBuilders()
                    .ifPresent(builders -> stream(builders).of(stream -> stream.forEach(innerHitBuilder::addSort)));

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

    /**
     * Get the value for the key 'query.collapse.inner.hits.sorts'. <br>
     * The value is, e.g.  <br>