load() Method

public void load()
    {
        try
        {
            FileInputStream file = new FileInputStream("bank.data");
            ObjectInputStream readThisFile = new ObjectInputStream(file);

            //The follow line is marked with a yellow warning:
            //Type safety: Unchecked cast from Object to List<Client>
            //What does it mean?

            clients = (List<Client>)readThisFile.readObject();

            readThisFile.close();
        }
        catch (Exception e)
        {
            e.getMessage();
            clients = new ArrayList<Client>();
        }
    }