/// <exception cref="System.IO.IOException"/>
 public virtual void ReadFields(DataInput @in)
 {
     inputSplitClass = (Type)ReadClass(@in);
     inputSplit      = (InputSplit)ReflectionUtils.NewInstance(inputSplitClass, conf);
     inputSplit.ReadFields(@in);
     inputFormatClass = (Type)ReadClass(@in);
     mapperClass      = (Type)ReadClass(@in);
 }