FormatableBitSet unresolvedColumns = (FormatableBitSet)columns.clone();
for (int i = unresolvedColumns.anySetBit();
i >= 0;
i = unresolvedColumns.anySetBit(i)) {
if (permittedColumns != null && permittedColumns.get(i)) {
// column i (zero-based here) accounted for:
unresolvedColumns.clear(i);
}