https://docs.mendix.com/howto/integration/publish-rest-service/ Section 3.5 “Create a NewEdit page for the orders, then add a data grid to the Order_NewEdit page that displays the OrderItems over an association. “ Should this be “Create a NewEdit page for the OrderItems, ...” because there is already an new-edit page for the order which was generated.
Here is a chance to propose a change to the docs.mendix.com for you. Click on the pencil at the top right:
that will take you to github
then click on the pencil:
Correct the typo, add a description and click
click the button to create a pull-request and then you wait and see a couple of days.