# System.Text.Json.Serialization

``` diff
 namespace System.Text.Json.Serialization {
     public enum JsonIgnoreCondition {
+        WhenWritingNull = 3,
     }
+    public enum JsonNumberHandling {
+        AllowNamedFloatingPointLiterals = 4,
+        AllowReadingFromString = 1,
+        Strict = 0,
+        WriteAsString = 2,
+    }
+    public sealed class JsonNumberHandlingAttribute : JsonAttribute {
+        public JsonNumberHandlingAttribute(JsonNumberHandling handling);
+        public JsonNumberHandling Handling { get; }
+    }
 }
```

