Jhipster : Rest API should return JSON with 2 level depth relationship

Question

I have a Jhipster web application, and I have a (native jhipster) rest GET API Resource, returning a ResponseEntity<List> data which are converted to JSON on frontend (for the native webpage generated by Jhipster).

On the model, I have a 2 level relationship : Father => Son => Grandson

And I would like to have the JSON returning the name of the father but I cant.

Example :

When the rest API is called to have the list of grandson, the result is :

[{
  id: 1,
  name: Joe
  son: {
    id: 1,
    name: Robert
  }
},
...
]

But I would like to have :

[{
  id: 1,
  name: Joe
  son: {
    id: 1,
    name: Robert
    father: {
      id: 777,
      name: Alfonse
    }
  }
},
...
]

I tried many different techniques but didn't manage to do it simply and still do not have a solution.

Has anyone of you encountered this and have a solution ?

Thank you very much

---

I tried to add a transient field "fatherName" in the "grandson" java model. With the getter returning the son.father.name and it worked but then I had a problem with the sort mecanism of the table because all the mecanisme of criteria and pageable parameters upto the repository JPA Spring could not work.