Update src/Microsoft.OpenApi/Models/OpenApiOperation.cs

Co-authored-by: Vincent Biret <[email protected]>

Author: millicentachieng

src/Microsoft.OpenApi/Models/OpenApiOperation.cs

@@ -283,7 +283,7 @@ public void SerializeAsV2(IOpenApiWriter writer)
                     .SelectMany(r => r.Value.Content?.Keys)
                     .Concat(
                         Responses
-                        .Where(r => r.Value.Reference != null && r.Value.Reference.HostDocument != null)
+                        .Where(static r => r.Value.Reference != null && r.Value.Reference.HostDocument != null)
                         .SelectMany(r => r.Value.GetEffective(r.Value.Reference.HostDocument)?.Content?.Keys))
                     .Distinct()
                     .ToList();