Ah ok! Of course for a view-only use case you don´t need to take care for the UI elements.
Your colleague I met was the same that presented the original onGet idea. So I was happy that he liked the CUI concept.
Some remarks: I currently use the following version of the above code, as the original version can produce a few strange side effects in certain scenarios
Item res = this.apply("get");
I can confirm that the onGet Method will also work for relationships. But I would recommed the version I posted above. But of course I would be happy to hear about experiences from others. In our environment the original version used in a Part relationship produced some problems in MPP. It wasn´t possible to drag'n'drop Parts in the Process Plan anymore, as the MPP somehow tried to read the federated content, but failed.