/** Logger instance for this class */
    private static final Logger logger = LogManager.getLogger(FtpClient.class);

    /** Metadata key for FTP file group */
    public static final String FTP_FILE_GROUP = "ftpFileGroup";

    /** Metadata key for FTP file user */
    public static final String FTP_FILE_USER = "ftpFileUser";

    /** Property name for FTP authentications */