title: OpenXML - how to save spreadsheetdocument to stream?
body: <p>I am getting an .xlsx document from a stream (using <code>SpreadsheetDocument.Open(stream, false)</code> then storing it into a Spreadsheetdocument field so that I can maintain the same object later.</p>
  
  <p>I have a save method where I should ideally be able to save the SpreadsheetDocument to a stream. There is <code>document..WorkbookPart.Workbook.Save(stream);</code> but that just gives me an empty file, and when I save only the first sheet (using <code>document.WorkbookPart.WorksheetParts.First().Worksheet.Save(stream);</code> the file is a mess and does not contain the relevant information. How do I save a spreadsheetdocument to a stream?</p>