final String source = fessConfig.getIndexReindexBody()//
                .replace("__SOURCE_INDEX__", fromIndex)//
                .replace("__SIZE__", fessConfig.getIndexReindexSize())//
                .replace("__DEST_INDEX__", toIndex)//
                .replace("__SCRIPT_SOURCE__", ComponentUtil.getLanguageHelper().getReindexScriptSource());

     * comment: Number of documents to process per reindex operation.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getIndexReindexSize();

    /**
     * Get the value for the key 'index.reindex.size' as {@link Integer}. <br>
     * The value is, e.g. 100 <br>
     * comment: Number of documents to process per reindex operation.