Optimize ODataPathExtensions.GetNavigationSource (#1161)

* Optimize GetNavigationSource source

* Use >= 0 instead of > -1

src/Microsoft.AspNetCore.OData/Routing/ODataPathExtensions.cs

@@ -77,9 +77,58 @@ public static IEdmNavigationSource GetNavigationSource(this ODataPath path)
                 throw Error.ArgumentNull(nameof(path));
             }
 
-            ODataPathNavigationSourceHandler handler = new ODataPathNavigationSourceHandler();
-            path.WalkWith(handler);
-            return handler.NavigationSource;
+            for (int i = path.Count - 1; i >= 0; --i)
+            {
+                ODataPathSegment segment = path[i];
+                if (segment is EntitySetSegment entitySetSegment)
+                {
+                    return entitySetSegment.EntitySet;
+                }
+
+                if (segment is KeySegment keySegment)
+                {
+                    return keySegment.NavigationSource;
+                }
+
+                if (segment is NavigationPropertyLinkSegment navigationPropertyLinkSegment)
+                {
+                    return navigationPropertyLinkSegment.NavigationSource;
+                }
+
+                if (segment is NavigationPropertySegment navigationPropertySegment)
+                {
+                    return navigationPropertySegment.NavigationSource;
+                }
+
+                if (segment is OperationImportSegment operationImportSegment)
+                {
+                    return operationImportSegment.EntitySet;
+                }
+
+                if (segment is OperationSegment operationSegment)
+                {
+                    return operationSegment.EntitySet;
+                }
+
+                if (segment is SingletonSegment singleton)
+                {
+                    return singleton.Singleton;
+                }
+
+                if (segment is TypeSegment typeSegment)
+                {
+                    return typeSegment.NavigationSource;
+                }
+
+                if (segment is PropertySegment)
+                {
+                    continue;
+                }
+
+                return null;
+            }
+
+            return null;
         }
 
         /// <summary>