Hello Pereira,

Thank you for providing the document link of igTreeGrid though I am afraid the link you provided is not outdated or an old version, even it is the most latest version 16.2 of Infragistics.

To refer the API document of igTreeGrid with version 16.1 you can refer the following link:

  http://www.igniteui.com/help/igtreegrid-load-on-demand?v=16.1

Please note when you will open this link you can see there is a version link on very top of the page when you will click on that link you can see all the versions list out there and you can choose any specific version to get the document belongs to that version.

At the bottom of the document you will get the sample of load on demand at child level in igTreeGrid .

I can also provide you the link of the sample as:

  http://www.igniteui.com/tree-grid/load-on-demand

 Please let me know if you need further assistance.