public FillStyleCacheItem(ExcelCellFillStyle format)
 {
     Color = new ColorCacheItem(format.Color ?? ExcelColors.White);
 }
 public BorderCacheItem(ExcelCellBorderStyle borderStyle)
 {
     borderType = borderStyle.BorderType;
     color      = new ColorCacheItem(borderStyle.Color ?? ExcelColors.Black);
 }