*/
    public void sendHeartbeat() {
        final long now = System.currentTimeMillis();
        final long ttl = ComponentUtil.getFessConfig().getCoordinatorHeartbeatTtlAsInteger().longValue();
        final String hostname = ComponentUtil.getSystemHelper().getHostname();
        final String targetName = ComponentUtil.getFessConfig().getSchedulerTargetName();

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

    /**
     * Get the value for the key 'coordinator.operation.ttl'. <br>
     * The value is, e.g. 7200000 <br>
     * comment: Time-to-live (ms) for operation lock documents.