@Override
    public void initialize(InputSplit split, TaskAttemptContext context)
      throws IOException, InterruptedException {
      WALSplit hsplit = (WALSplit) split;
      logFile = new Path(hsplit.getLogFileName());
      conf = context.getConfiguration();
      LOG.info("Opening {} for {}", logFile, split);
      openReader(logFile);
      this.startTime = hsplit.getStartTime();
      this.endTime = hsplit.getEndTime();
    }
{@link RecordReader} for an {@link WAL} file. Implementation shared with deprecated
HLogInputFormat.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/WALInputFormat.java