Simplify DecodeStructuredModeDataProperty and add unit test to cover code path

src/CloudNative.CloudEvents.SystemTextJson/JsonEventFormatter.cs

@@ -704,9 +704,7 @@ protected override void EncodeStructuredModeData(CloudEvent cloudEvent, Utf8Json
 
     /// <inheritdoc />
     protected override void DecodeStructuredModeDataProperty(JsonElement dataElement, CloudEvent cloudEvent) =>
-        // Note: this is an inefficient way of doing this.
-        // See https://github.com/dotnet/runtime/issues/31274 - when that's implemented, we can use the new method here.
-        cloudEvent.Data = JsonSerializer.Deserialize<T>(dataElement.GetRawText(), SerializerOptions);
+        cloudEvent.Data = JsonSerializer.Deserialize<T>(dataElement, SerializerOptions);
 
     // TODO: Consider decoding the base64 data as a byte array, then using DecodeBinaryModeData.
     /// <inheritdoc />

test/CloudNative.CloudEvents.UnitTests/SystemTextJson/GenericJsonEventFormatterTest.cs

@@ -8,6 +8,7 @@
 using System.Net.Mime;
 using System.Text;
 using System.Text.Json;
+using System.Text.Json.Serialization;
 using Xunit;
 
 namespace CloudNative.CloudEvents.SystemTextJson.UnitTests;
@@ -45,6 +46,22 @@ public void DecodeStructuredMode_ContentTypeIgnored()
         Assert.Equal("test", model.AttributedProperty);
     }
 
+    [Fact]
+    public void DecodeStructuredMode_UsesSerializerOptions()
+    {
+        var obj = JsonEventFormatterTest.CreateMinimalValidJObject();
+        obj["data"] = "10";
+        byte[] bytes = Encoding.UTF8.GetBytes(obj.ToString());
+
+        var formatter = new JsonEventFormatter<int>(new JsonSerializerOptions
+        {
+            NumberHandling = JsonNumberHandling.AllowReadingFromString
+        }, default);
+        var cloudEvent = formatter.DecodeStructuredModeMessage(bytes, null, null);
+
+        Assert.Equal(10, cloudEvent.Data);
+    }
+
     [Fact]
     public void DecodeStructuredMode_NoData()
     {