*
     * @return the number of filter replicas
     */
    @Override
    public int getFilterReplicas() {
        return ComponentUtil.getFessConfig().getIndexDocumentCrawlerFilterNumberOfReplicasAsInteger();
    }

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

    /**
     * Get the value for the key 'index.config.index'. <br>
     * The value is, e.g. fess_config <br>
     * comment: Index name for configuration data.