java cleanDirectory() how to make directory path OS idependent

Please, help me with solution. I'm testing the files downloading process and to clear up the Downloads directory using in @AfterClass cleanDirectory() on MAC OS

@AfterClass
public static void clearDownloadDirectory() throws IOException{
    FileUtils.cleanDirectory(new File("/Users/irina/Downloads"));
}

How to make the Downloads directory path platform independent so it could work for Windows too?

Maybe I'm looking for the answer in a wrong way. Primary thing I need is to delete all xlsx files from the Downloads folder.

Depending on your app you can use System.getProperty("os.name").

Maybe like this

//...
String url;
switch( System.getProperty("os.name") ) {
    case "Windows 8.1":
    case "Windows Vista":
    //etc for all windows systems
    {
      url = "C:/Users/user_name/downloads..."
      break;
    }
    case "Mac OS X": //...
    case "SunOS": //...
    case "Linux": //...
    //etc all systems you want to support
}

EDIT

Also System.getProperty("user.home") can help you

"user.home" User home directory

Java System properties list