UnityEditor.SerializedObject.ApplyModifiedPropertiesWithoutUndo C# (CSharp) Method

        public extern bool ApplyModifiedPropertiesWithoutUndo();
        [MethodImpl(MethodImplOptions.InternalCall)]

    public static void CreateNewGameLevel()
    {
        // Ask the user if they would like to save the current scene if need be, if they do not press cancel...
        if (EditorApplication.SaveCurrentSceneIfUserWantsTo())
        {
            // ... then load a new scene.
            EditorApplication.NewScene();

            // We do not want the default `Main Camera` object do destroy that.
            Object.DestroyImmediate(GameObject.Find("Main Camera"));

            // For each required prefab file name...
            foreach (string levelRequirement in LevelRequirementPrefabs)
            {
                // ... load the prefab from the asset database.
                GameObject requiredPrefab = AssetDatabase.LoadAssetAtPath<GameObject>(RootLevelRequirements + levelRequirement);

                // Instantiate it within the new scene connected to the prefab.
                PrefabUtility.InstantiatePrefab(requiredPrefab);
            }

            // Reference the objects that need connecting to each other.
            EndOfLevel endOfLevel = Object.FindObjectOfType<EndOfLevel>();
            LevelController levelController = Object.FindObjectOfType<LevelController>();
            CameraController cameraController = Object.FindObjectOfType<CameraController>();
            Player player = Object.FindObjectOfType<Player>();

            // Disconect required objects from prefabs if appropriate to do so.
            PrefabUtility.DisconnectPrefabInstance(endOfLevel);

            // Create a new serialized object of the end of level.
            SerializedObject serializedEndOfLevel = new SerializedObject(endOfLevel);

            // Set the appropriate properties to their correct values.
            serializedEndOfLevel.FindProperty("menuSwitcher").objectReferenceValue = Object.FindObjectOfType<MenuSwitcher>();

            // Apply the changed properties without an undo.
            serializedEndOfLevel.ApplyModifiedPropertiesWithoutUndo();

            // Create a new serialized object of the level controller.
            SerializedObject serializedLevelController = new SerializedObject(levelController);

            // Set the appropriate properties to their correct values.
            serializedLevelController.FindProperty("cameraController").objectReferenceValue = cameraController;
            serializedLevelController.FindProperty("player").objectReferenceValue = player;

            // Apply the changed properties without an undo.
            serializedLevelController.ApplyModifiedPropertiesWithoutUndo();

            // Create a new serialized object of the camera controller.
            SerializedObject serializedCameraController = new SerializedObject(cameraController);

            // Set the appropriate properties to their correct values.
            serializedCameraController.FindProperty("target").objectReferenceValue = player.GetComponent<CameraTarget>();

            // Apply the changed properties without an undo.
            serializedCameraController.ApplyModifiedPropertiesWithoutUndo();
        }
    }