@Override
    public Path getPath() {
      if (inputSplit instanceof FileSplit) {
        return ((FileSplit) inputSplit).getPath();
      }
      throw new RuntimeException(inputSplit + " is not a FileSplit");
    }
HiveInputSplit encapsulates an InputSplit with its corresponding
inputFormatClass. The reason that it derives from FileSplit is to make sure
"map.input.file" in MapTask.
ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java