Merge pull request #371 from yehiaelsayed/FixIncluedOptimizedIssueWithEFInheritance(TPT)

Fix IncludeOptimized function issue with EF Inheritance (TPT)

Author: JonathanMagnan

src/shared/Z.EF.Plus.QueryIncludeOptimized.Shared/QueryIncludeOptimizedProvider.cs

@@ -195,7 +195,7 @@ public TResult Execute<TResult>(Expression expression)
                     // MODIFY query if necessary
 #if EF5 || EF6
                     var objectContext = CurrentQueryable.OriginalQueryable.GetObjectQuery().Context;
-                    var keyMembers = ((dynamic)objectContext).CreateObjectSet<T>().EntitySet.ElementType.KeyMembers;
+                    var keyMembers = objectContext.GetEntitySet<T>().ElementType.KeyMembers;
                     var keyNames = ((IEnumerable<EdmMember>)keyMembers).Select(x => x.Name).ToArray();
 #elif EFCORE