String QUERY_LANGUAGE_MAPPING = "queryLanguageMapping";

    String CRAWLER_METADATA_NAME_MAPPING = "crawlerMetadataNameMapping";

    String CRAWLER_METADATA_CONTENT_EXCLUDES = "crawlerMetadataContentExcludes";

    Map<String, Object> propMap = new ConcurrentHashMap<>();

    String getOrDefault(String propertyKey, String defaultValue);

    //
    // system.properties
    //