code: @Override
     public PropertyDescriptor findDescriptor(int col) throws IntrospectionException {
        String columnName = getColumnName(col);
        return (StringUtil.trimToNull(columnName) != null) ? findDescriptor(columnName) : null;
     }
docs: Gets the property descriptor for a given column position.
  @param col the column to find the description for
  @return - the property descriptor for the column position or null if one could not be found.
  @throws IntrospectionException - thrown on error retrieving the property description.