final FessConfig fessConfig = ComponentUtil.getFessConfig();
        final Map<String, String> paramEnvMap = systemHelper.getFilteredEnvMap(fessConfig.getCrawlerDataEnvParamKeyPattern());
        final Map<String, String> configParamMap = config.getHandlerParameterMap().entrySet().stream().map(e -> {
            final String key = e.getKey();
            String value = e.getValue();

     * comment: Pattern for environment variable keys in crawling data.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getCrawlerDataEnvParamKeyPattern();

    /**
     * Get the value for the key 'crawler.ignore.robots.txt'. <br>
     * The value is, e.g. false <br>
     * comment: Whether to ignore robots.txt during crawling.