code: @Override
      public Pair<Map<String, ByteBuffer>, Map<String, ByteBuffer>> next() {
          if (!this.hasNext()) {
              throw new DeepIllegalAccessException("DeepRecordReader exhausted");
          }
          return rowIterator.next();
      }
docs: Returns the next element in the underlying rowIterator.
  
  @return the next element in the underlying rowIterator.