}
// the swap is on the index column. it will only succeed if the current
// value matches the expected value of the swap. if that value is not null,
// then we must remove the row key from the index for that value.
Delete idxDelete = null;
if (expected != null) {
idxDelete = new Delete(createIndexKey(row, column, expected), IDX_COL);
}
// if the new value is not null, then we must add the rowkey to the index
// for that value.
Put idxPut = null;