docs: public ColumnValueSelector<?> makeColumnValueSelector(String columnName, ColumnSelectorFactory factory)
    {
      final VirtualColumn virtualColumn = getVirtualColumn(columnName);
      if (virtualColumn == null) {
        throw new IAE("No such virtual column[%s]", columnName);
      } else {
        final ColumnValueSelector<?> selector = virtualColumn.makeColumnValueSelector(columnName, factory);
        Preconditions.checkNotNull(selector, "selector");
        return selector;
      }
    }