TableColumnWidth defaultColumnWidth

How to determine with widths of columns that don't have an explicit sizing algorithm.

Specifically, the defaultColumnWidth is used for column i if columnWidths[i] is null.

Source 

TableColumnWidth get defaultColumnWidth => _defaultColumnWidth;
void defaultColumnWidth=(TableColumnWidth value)

Source 

set defaultColumnWidth(TableColumnWidth value) {
  assert(value != null);
  if (defaultColumnWidth == value)
    return;
  _defaultColumnWidth = value;
  markNeedsLayout();
}