* It extends {@link AbstractCrawlerClient} and provides methods to retrieve content and metadata
 * from FTP servers. The client supports various configurations, including authentication, timeouts,
 * passive/active modes, and encoding settings. It also handles FTP file attributes such as user,
 * group, and symbolic links.
 *
 * <p>
 * The class uses Apache Commons Net library for FTP communication. It maintains a queue of FTPClient