@Override
      public float getProgress() throws IOException {
        return trr.getProgress();
      }
Builds a TableRecordReader. If no TableRecordReader was provided, uses the default.
@see InputFormat#getRecordReader(InputSplit, JobConf, Reporter)
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapred/TableInputFormatBase.java