<PackageReference Include="NETStandard.Library" Version="2.0.1" />

System.Text.UTF8Encoding

public class UTF8Encoding : Encoding
namespace System.Text { public class UTF8Encoding : Encoding { public UTF8Encoding(); public UTF8Encoding(bool encoderShouldEmitUTF8Identifier); public UTF8Encoding(bool encoderShouldEmitUTF8Identifier, bool throwOnInvalidBytes); } }