GET /rest/servicedeskapi/request/{issueIdOrKey} does not return hidden summary

Issue Summary

The customer portal UI always shows summary for a submitted request, even when the summary field is made a hidden field. The equivalent REST API call, GET /rest/servicedeskapi/request/issueIdOrKey, does not act consistently with the UI.

Steps to Reproduce

Given:

1. Go to a Project -> Project settings -> Request types -> click any of your request types
2. Go to the tab "Request form"
3. Scroll to the section "Visible fields". Find the field which is mapped to the Summary field (normally this is the first one in the list)
4. Click "Hide"
5. A pop-up appears which asks you to set a preset value
6. Log in as a JSD customer to the corresponding issue
7. Start a new request for the appropriate type (matching what admin would have changed from step 1). The summary field is not shown.
8. Finish the request and see the completed request in the customer portal. The summary field is shown. Note the request Key.

Then:

1. Now execute the equivalent API request: GET /rest/servicedeskapi/request/ {Key}

Expected Results

The API returns the following, consistent with the UI:

{
  ...
 "requestFieldValues": [
    {
      "fieldId": "summary",
      "label": "What do you need?",
      "value": "Request JSD help via REST"
    },
    ...
  ],
  ...
}

Actual Results

The summary field is missing in the response.

Workaround

Some API clients (Connect Apps) may be able to follow the jiraRest URL to obtain the summary from the underlying issue using the platform API.