X-CORRELATION-ID and X-REFERRER not documented in Rest contract

[pnbecker]

https://github.com/DSpace/DSpace/pull/3303 introduced a header X-CORRELATION-ID and X-REFERRER. The correlation id shows up in almost every log entry in the backend. Unfortunately, it is not documented in the RestContract. The corresponding PR for dspace-angular seems to be https://github.com/DSpace/dspace-angular/pull/1255.

[tdonohue]

Good catch, I agree it should be added.

These headers are NOT required for a client, but they are used in backend logging in order to be able to "track" a user's session and what UI page generated a request to the backend. The basic description is in the description of that UI PR: https://github.com/DSpace/dspace-angular/pull/1255

• X-CORRELATION-ID is a randomly generated UUID optionally sent by the client, and assumed to be "kept stable" for a single user session. It can be used as a form of "session ID" in the backend logs, allowing an administrator to be able to understand the activities of a single user session without tracking identifiable information. If not specified, the logs will say "unknown".
• X-REFERRER contains the user interface (client) path (e.g. /item/[uuid] for an Item page) that generated the REST request. This serves a similar purpose as the Referer HTTP Header, but is used because the Referer HTTP Header is sometimes modified by browsers. This header is again only used for backend logs, to allow administrators to understand which User Interface page generated the REST API request. It is also optional, and if missing will say "unknown".

Needs a volunteer to pull this into official RestContract docs. These are just my rough notes of what I am aware to be true.