Minor Description
After creating FTPClient you are able to invoke org.apache.commons.net.SocketClient-> setSoTimeout () method which will result in NullPointerException.
It happens because in SocketClient class Socket object is initialized with null. Shouldn't it be more sensible to create new socket from the socketFactory and don't wait for socket creation till connect() method, because it will be imposiible to do any configuration to the socket until you're connected.