/** The key of the configuration. e.g. true */
    String RESPONSE_HIGHLIGHT_content_title_ENABLED = "response.highlight.content_title.enabled";

    /** The key of the configuration. e.g. application/pdf,text/plain */
    String RESPONSE_INLINE_MIMETYPES = "response.inline.mimetypes";

    /** The key of the configuration. e.g. fess.search */
    String INDEX_DOCUMENT_SEARCH_INDEX = "index.document.search.index";