* comment: Interval (ms) for heartbeat checks to the search engine.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getSearchEngineHeartbeatInterval();

    /**
     * Get the value for the key 'search_engine.heartbeat_interval' as {@link Integer}. <br>
     * The value is, e.g. 10000 <br>