dotnet-core/release-notes/2.1/api-diff/2.0-vs-2.1_System.Net.Mime.md

System.Net.Mime

 namespace System.Net.Mime {
     public static class MediaTypeNames {
         public static class Application {
+            public const string Json = "application/json";
+            public const string Xml = "application/xml";
         }
     }
 }