NPOI.XSSF.UserModel.XSSFWorkbook.newPackage C# (CSharp) Метод

        protected static OPCPackage newPackage()
        {
            try
            {
                OPCPackage pkg = OPCPackage.Create(new MemoryStream());
                // Main part
                PackagePartName corePartName = PackagingUriHelper.CreatePartName(XSSFRelation.WORKBOOK.DefaultFileName);
                // Create main part relationship
                pkg.AddRelationship(corePartName, TargetMode.Internal, PackageRelationshipTypes.CORE_DOCUMENT);
                // Create main document part
                pkg.CreatePart(corePartName, XSSFRelation.WORKBOOK.ContentType);

                pkg.GetPackageProperties().SetCreatorProperty(DOCUMENT_CREATOR);

                return pkg;
            }
            catch (Exception e)
            {
                throw new POIXMLException(e);
            }
        }

 public XSSFWorkbook()
     : base(XSSFWorkbook.newPackage())
 {
     this.OnWorkbookCreate();
 }