[FTP/FTPS Only] Completes the asynchronous operation started in BeginGetSystemType.
The type of server operating system.
Before calling BeginGetSystemType, you need to create a callback method that implements the AsyncCallback delegate. This callback method executes in a separate thread and is called by the system after BeginGetSystemType returns. The callback method must accept the IAsyncResult returned by the BeginGetSystemType method as a parameter. This parameter may then be passed to the EndGetSystemType method to complete the operation.