Confusion around selecting fields from relationships

[Offlein]

I'm having a lot of difficulty with this library and how it's intended to be used.

I have an Inventory table and an inventoryRequest relation. All my tables have id columns that are internal-only, as well as public-facing unique display_id columns.

Ideally I want to specify only certain fields on both the Inventory and the inventoryRequest relationship to be allowed. It is incredibly confusing to me that QueryBuilder's ->allowedFields() method defaults to including all Model properties, even when they're not "allowed", but I at least can deal with it, sort of, with the ->query()->select() workaround.

As it stands, if I make a request like this:

?include=inventoryRequest&fields[inventoryRequest]=display_id

I get a request that completely ignores my fields constraint. (Same if I format the query param like fields=inventoryRequest.display_id)

The response looks like this:

[
  {
    "id": 1,
    "display_id": "ABC123",
    "rfp_operator_id": 1,
    "inventory_request_id": 16,
    ...all other properties...,
    "operator_request": {
      "id": 16,
      "display_id": "PZLLH6A",
      ...all other properties...,
    },
    ...
  },
  ...,
]

At this point I am wondering if it's just a bug with the library. I can do a query like:

?include=inventoryRequest&fields[inventoryRequest]=display_id&fields=display_id,inventory_request_id

And it will filter the top-level objects to only have display_id, but the inventoryRequest relationship will be the full model data again.