private static void checkProperty(int columnNumber, ColumnAttributes col)
{
if (col == null)
throw new ArgumentNullException("col");
if (string.IsNullOrEmpty(col.PropertyName))
{
throw new InvalidOperationException(string.Format(CultureInfo.InvariantCulture,
"pdfColumnsDefinitions[{0}].PropertyName is empty.", columnNumber));
}
}