VFS provides no easy/robust way to have setRemoteVerificationEnabled(..) called on the org.apache.commons.net.ftp.FTPClient instances that it creates.
This is a problem for me because I need to call setRemoteVerificationEnabled(false) for my application to work correctly.
In order to call this method I had to extend FtpFileProvider and FtpFileSystem, and I had to completely copy and paste FtpClientWrapper to create my own variant that calls setRemoteVerificationEnabled(..) on its wrapped FTPClient.
This situation could be improved by augmenting FtpFileSystemConfigBuilder to add a remote verification option. I found an old patch to do this: http://apache-commons.680414.n4.nabble.com/VFS-PATCH-Allow-configuration-of-FTP-remote-verification-td716436.html