fix: callback reference annotations parsing

Signed-off-by: Vincent Biret <[email protected]>

Author: baywet

src/Microsoft.OpenApi/Reader/V31/OpenApiCallbackDeserializer.cs

@@ -22,10 +22,12 @@ public static IOpenApiCallback LoadCallback(ParseNode node, OpenApiDocument host
         {
             var mapNode = node.CheckMapNode("callback");
 
-            if (mapNode.GetReferencePointer() is {} pointer)
+            if (mapNode.GetReferencePointer() is { } pointer)
             {
                 var reference = GetReferenceIdAndExternalResource(pointer);
-                return new OpenApiCallbackReference(reference.Item1, hostDocument, reference.Item2);
+                var callbackReference = new OpenApiCallbackReference(reference.Item1, hostDocument, reference.Item2);
+                callbackReference.Reference.SetMetadataFromMapNode(mapNode);
+                return callbackReference;
             }
 
             var domainObject = new OpenApiCallback();

test/Microsoft.OpenApi.Readers.Tests/V31Tests/OpenApiCallbackReferenceDeserializerTests.cs

@@ -0,0 +1,36 @@
+using System.Text.Json.Nodes;
+using Microsoft.OpenApi.Reader;
+using Microsoft.OpenApi.Reader.V31;
+using Xunit;
+
+namespace Microsoft.OpenApi.Readers.Tests.V31Tests;
+
+public class OpenApiCallbackReferenceDeserializerTests
+{
+    [Fact]
+    public void ShouldDeserializeCallbackReferenceAnnotations()
+    {
+        var json =
+        """
+        {
+            "$ref": "#/components/callbacks/MyCallback"
+        }
+        """;
+
+        var hostDocument = new OpenApiDocument();
+        hostDocument.AddComponent("MyCallback", new OpenApiCallback
+        {
+            // Optionally add a PathItem or similar here if needed
+        });
+        var jsonNode = JsonNode.Parse(json);
+        var parseNode = ParseNode.Create(new ParsingContext(new()), jsonNode);
+
+        var result = OpenApiV31Deserializer.LoadCallback(parseNode, hostDocument);
+
+        Assert.NotNull(result);
+        var resultReference = Assert.IsType<OpenApiCallbackReference>(result);
+
+        Assert.Equal("MyCallback", resultReference.Reference.Id);
+        Assert.NotNull(resultReference.Target);
+    }
+}