# System.Text.Json.Serialization

``` diff
 namespace System.Text.Json.Serialization {
     public enum JsonKnownNamingPolicy {
+        KebabCaseLower = 4,
+        KebabCaseUpper = 5,
+        SnakeCaseLower = 2,
+        SnakeCaseUpper = 3,
     }
+    public enum JsonUnmappedMemberHandling {
+        Disallow = 1,
+        Skip = 0,
+    }
+    [AttributeUsageAttribute(AttributeTargets.Class | AttributeTargets.Interface | AttributeTargets.Struct, AllowMultiple=false, Inherited=false)]
+    public class JsonUnmappedMemberHandlingAttribute : JsonAttribute {
+        public JsonUnmappedMemberHandlingAttribute(JsonUnmappedMemberHandling unmappedMemberHandling);
+        public JsonUnmappedMemberHandling UnmappedMemberHandling { get; }
+    }
 }
```

