<PackageReference Include="System.ServiceModel.Primitives" Version="6.1.0" />

System.Xml.XmlMtomWriter

namespace System.Xml { internal class XmlMtomWriter : XmlDictionaryWriter, IXmlMtomWriterInitializer { public static XmlDictionaryWriter Create(Stream stream, Encoding encoding, int maxSizeInBytes, string startInfo); public static XmlDictionaryWriter Create(Stream stream, Encoding encoding, int maxSizeInBytes, string startInfo, string boundary, string startUri, bool writeMessageHeaders, bool ownsStream); public XmlMtomWriter(); public void SetOutput(Stream stream, Encoding encoding, int maxSizeInBytes, string startInfo, string boundary, string startUri, bool writeMessageHeaders, bool ownsStream); public static string GenerateUriForMimePart(int index); } }