// For complete examples and data files, please go to https://github.com/aspose-cells/Aspose.Cells-for-Java // The path to the directories. String outputDir = Utils.Get_OutputDirectory(); Workbook workbook = new Workbook(FileFormatType.XLSX); int index = workbook.getContentTypeProperties().add("MK31", "Simple Data"); workbook.getContentTypeProperties().get(index).setNillable(false); index= workbook.getContentTypeProperties().add("MK32", "2019-10-17T16:00:00+00:00", "DateTime"); workbook.getContentTypeProperties().get(index).setNillable(false); workbook.save(outputDir + "WorkingWithContentTypeProperties_out.xlsx");