code: @Override
    public Tuple getNext() throws IOException {
      if (reader == null) {
        return null;
      }
      // nested load can be enabled through a pig property
      if ("true".equals(jobConf.get(NESTED_LOAD_KEY)))
        isNestedLoadEnabled = true;
      try {
        while (reader.nextKeyValue()) {
          Text value = (Text) reader.getCurrentValue();
          incrCounter(JsonLoaderCounters.LinesRead, 1L);
          Tuple t = parseStringToTuple(value.toString());
          if (t != null) {
            incrCounter(JsonLoaderCounters.LinesJsonDecoded, 1L);
            return t;
          }
        }
        return null;
  
      } catch (InterruptedException e) {
        int errCode = 6018;
        String errMsg = "Error while reading input";
        throw new ExecException(errMsg, errCode,
            PigException.REMOTE_ENVIRONMENT, e);
      }
    }
docs: Return every non-null line as a single-element tuple to Pig.