fix: parameter reference annoation parsing

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

Author: baywet

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

@@ -161,7 +161,9 @@ public static IOpenApiParameter LoadParameter(ParseNode node, OpenApiDocument ho
             if (pointer != null)
             {
                 var reference = GetReferenceIdAndExternalResource(pointer);
-                return new OpenApiParameterReference(reference.Item1, hostDocument, reference.Item2);
+                var parameterReference = new OpenApiParameterReference(reference.Item1, hostDocument, reference.Item2);
+                parameterReference.Reference.SetMetadataFromMapNode(mapNode);
+                return parameterReference;
             }
 
             var parameter = new OpenApiParameter();

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

@@ -0,0 +1,40 @@
+using System.Text.Json.Nodes;
+using Microsoft.OpenApi.Reader;
+using Microsoft.OpenApi.Reader.V31;
+using Xunit;
+
+namespace Microsoft.OpenApi.Readers.Tests.V31Tests;
+
+public class OpenApiParameterReferenceDeserializerTests
+{
+    [Fact]
+    public void ShouldDeserializeParameterReferenceAnnotations()
+    {
+        var json =
+        """
+        {
+            "$ref": "#/components/parameters/MyParameter",
+            "description": "This is a parameter reference"
+        }
+        """;
+
+        var hostDocument = new OpenApiDocument();
+        hostDocument.AddComponent("MyParameter", new OpenApiParameter
+        {
+            Name = "myParam",
+            In = ParameterLocation.Query,
+            Description = "This is a parameter description",
+        });
+        var jsonNode = JsonNode.Parse(json);
+        var parseNode = ParseNode.Create(new ParsingContext(new()), jsonNode);
+
+        var result = OpenApiV31Deserializer.LoadParameter(parseNode, hostDocument);
+
+        Assert.NotNull(result);
+        var resultReference = Assert.IsType<OpenApiParameterReference>(result);
+
+        Assert.Equal("MyParameter", resultReference.Reference.Id);
+        Assert.Equal("This is a parameter reference", resultReference.Description);
+        Assert.NotNull(resultReference.Target);
+    }
+}