protected void flattenRepeatingNulls(boolean selectedInUse, int[] sel,
                                       int size) {

    boolean nullFillValue;

    if (noNulls) {
      nullFillValue = false;
    } else {
      nullFillValue = isNull[0];
    }

    if (selectedInUse) {
      for (int j = 0; j < size; j++) {
        int i = sel[j];
        isNull[i] = nullFillValue;
      }
    } else {
      Arrays.fill(isNull, 0, size, nullFillValue);
    }

    // all nulls are now explicit
    noNulls = false;
  }
Sets the isRepeating flag. Recurses over structs and unions so that the
flags are set correctly.
@param isRepeating flag for repeating value.
storage-api/src/java/org/apache/hadoop/hive/ql/exec/vector/ColumnVector.java