private Task WriteDocumentAsync(XmlWriter writer) { // declare the atom10 namespace upfront for compactness writer.WriteAttributeString(Atom10Constants.Atom10Prefix, Atom10FeedFormatter.XmlNsNs, Atom10Constants.Atom10Namespace); return(AtomPub10ServiceDocumentFormatter.WriteCategoriesInnerXml(writer, this.Document, null, this.Version)); }