Scene don't show change when create gameobject by custom script

When i use menu GameObject/Create Empty, in hierarchy will add 1 gameobject and the scene header will show a symbol to indicate that the scene has changes like attached file. But when i use custom menu script to create gameobject :

[MenuItem("Test/Custom GameObject")]
public static void CreateCustomGameObject()
{
GameObject obj = new GameObject();
}

in hierarchy will add 1 gameobject but the scene header don't show any symbol to indicate that the scene has changes. If i close unity now, next times when i open unity, the gameobject that i created by custom menu script is not there anymore! How can i force scene to has change and i can save it so next times i won't lose the gameobject anymore

 

If you add the action to the undo stack, it should do the trick.

 

can you give me sample code for it ?

 

https://docs.unity3d.com/ScriptReference/Undo.html