When i try using XSSFWorkbook class to open an .xlsx file, it throws error of 4RedToBlack not found from NPOI.OpenXml4Net.dll if any sheet in that file has conditional formatting in some cells.
```
using (FileStream file = new FileStream(importingModel.FilePath, FileMode.Open, FileAccess.Read))
{
var xssfworkbook = new XSSFWorkbook(file);
ParseSheetsToModel(importingModel, xssfworkbook);
}
```
The exception occurred at the line: var xssfworkbook = new XSSFWorkbook(file);
If i remove all conditional format rules in all sheets of the xlsx file. The class works fine then.
```
using (FileStream file = new FileStream(importingModel.FilePath, FileMode.Open, FileAccess.Read))
{
var xssfworkbook = new XSSFWorkbook(file);
ParseSheetsToModel(importingModel, xssfworkbook);
}
```
The exception occurred at the line: var xssfworkbook = new XSSFWorkbook(file);
If i remove all conditional format rules in all sheets of the xlsx file. The class works fine then.