Aliased Attribute Names Are Not Used In Error Responses

This issue is a (choose one):

• [X ] Problem/bug report.
• Feature request.
• Request for support. Note: Please try to avoid submitting issues for support requests. Use Gitter instead.

Checklist before submitting:

• [ X] I've searched for an existing issue.
• I've asked my question on Gitter and have not received a satisfactory answer.
• I've included a complete bug report template. This step helps us and allows us to see the bug without trying to reproduce the problem from your description. It helps you because you will frequently detect if it's a problem specific to your project.
• [ X] The feature I'm asking for is compliant with the JSON:API spec.

Description

I have a model with an attribute named status_is_active. In the API we want this to render as active so do the following in the resource:

attribute :active, delegate: :status_is_active

If there is an API error related to this attribute, the error reports the name from the model rather than the name from the resource. For example:

{
  "errors": [
    {
      "title": "is not included in the list",
      "detail": "status_is_active - is not included in the list",
      "code": "100",
      "source": {
          "pointer": "/data/attributes/status_is_active"
      },
      "status": "422"
    }
  ]
}

Expected: the error uses the name of the attribute in the resource rather than the name used in the model. For example:

{
  "errors": [
    {
      "title": "is not included in the list",
      "detail": "active - is not included in the list",
      "code": "100",
      "source": {
          "pointer": "/data/attributes/active"
      },
      "status": "422"
    }
  ]
}

Rationale: users of the API only know about what's in the API - returning a value from the model that is aliased in the API is confusing/wrong.

Thanks!

No implementation files or tests are named. Reproduce the delegated attribute :active, delegate: :status_is_active case and trace how validation errors are serialized; done means both the error detail and JSON:API source pointer use active instead of status_is_active.