Remove iterator allocation from Select() in hot path

Author: bkoelman

src/JsonApiDotNetCore/Serialization/Response/ResourceObjectTreeNode.cs

@@ -184,11 +184,11 @@ public IList<ResourceObject> GetResponseIncluded()
         HashSet<ResourceObject> primaryResourceObjectSet = GetDirectChildren().Select(node => node.ResourceObject).ToHashSet(ResourceObjectComparer.Instance);
         List<ResourceObject> includes = [];
 
-        foreach (ResourceObject include in visited.Select(node => node.ResourceObject))
+        foreach (ResourceObjectTreeNode include in visited)
         {
-            if (!primaryResourceObjectSet.Contains(include))
+            if (!primaryResourceObjectSet.Contains(include.ResourceObject))
             {
-                includes.Add(include);
+                includes.Add(include.ResourceObject);
             }
         }