/** The key of the configuration. e.g. thumbnail */
    String INDEX_FIELD_THUMBNAIL = "index.field.thumbnail";

    /** The key of the configuration. e.g. virtual_host */
    String INDEX_FIELD_virtual_host = "index.field.virtual_host";

    /** The key of the configuration. e.g. content_title */
    String RESPONSE_FIELD_content_title = "response.field.content_title";