PUT endpoint does not return correct id (maybe rowid?)

Bug or feature request

• [X ] Bug
• Feature request

Description of feature (or steps to reproduce if bug)

Create a model with an id as type "string", and a defaultFN of "uuid". PUT a new instance using the REST api through explorer. The response body will show an integer id (presumably an integer that corresponds to the ROWID or something like that). Now use the GET api to list all model instances. The instance will show an id in the correct uuid format.

Link to sample repo to reproduce issue (if bug)

Expected result

I'm assuming the response body should reflect the id generated by defaultFN.

Actual result (if bug)

Its an integer.

Additional information (Node.js version, LoopBack version, etc)

Loopback 3, node 8.11.2

I'm anticipating a reply of "why are you using a string for a key?" The answer is complicated based in integration with a larger project. If the answer is "we don't support that" we'll make it work, but I wanted to check to make sure. Thanks

Tái hiện trường hợp LoopBack 3 bằng cách tạo một model với id kiểu string và uuid defaultFN, sau đó gửi một instance mới qua PUT trong REST API Explorer. So sánh phản hồi PUT với id được trả về khi liệt kê các instance qua GET; được xem là hoàn tất khi phản hồi PUT trả về UUID đã tạo thay vì một số nguyên.