Hi, it's me again :D
I've come with another mystery for you Jason !
Here's my code :
SpreadsheetMLPackage pkg = SpreadsheetMLPackage.createPackage();
factory = Context.getsmlObjectFactory();
Styles styles = new Styles(new PartName("/xl/styles.xml"));
styles.setJaxbElement(createStyles());
pkg.addTargetPart(styles);
WorksheetPart sheet = pkg.createWorksheetPart(new PartName("/xl/worksheets/sheet1.xml"), "Sheet 1", 1);
SheetData sheetData = sheet.getJaxbElement().getSheetData();
for(int i = 0; i < 5; i++)
{
Row row = factory.createRow();
for(int j = 0; j < 5; j++) ...