dotnet-core/release-notes/3.0/api-diff/Asp.Net/3.0.0_Microsoft.AspNetCore.Razor.md

Microsoft.AspNetCore.Razor

 {
     namespace Microsoft.AspNetCore.Razor.TagHelpers {
-        public class NullHtmlEncoder : HtmlEncoder {
+        public sealed class NullHtmlEncoder : HtmlEncoder {
-            protected NullHtmlEncoder();

         }
-        public class RestrictChildrenAttribute : Attribute
+        public sealed class RestrictChildrenAttribute : Attribute
     }
 }