Issue Summary

Doing a PATCH or a PUT request to rest/align/api/2/Epics/EpicId endpoint to add a link to a work item will return the error :

"Cannot update epic with id EpicId. Cannot update links. Id shouldn't be empty."

Steps to Reproduce

Make a PATCH request to rest/align/api/2/Epics/EpicId endpoint with the following body:

[
  {
    "op": "add",
    "path": "/links/0",
    "value": {
       "name": "linkymclinkface",
       "link": "somelink.com"
    }
  }
] 

OR

Make a PUT request to rest/align/api/2/Epics/EpicId endpoint with the following body:

{
    "title": "TestLink4Epic",
    "ownerId": "<ownerId>",
    "description": "TestLink4Epic",
    "primaryProgramId": <programId>,
    "state": 1,
    "type": 1,
    "links": [
        {
            "name": "linkymclinkface",
            "link": "somelink.com"
        }
    ]
}

Expected Results

PATCH method operations should work with additional links 

The add operation should return an error if a linkId is provided

Actual Results

The error "Cannot update epic with id EpicId. Cannot update links. Id shouldn't be empty." is returned.

Workaround

Specify an id (made up) in the request of the body.
For example for the PATCH request:

[
  {
    "op": "add",
    "path": "/links/0",
    "value": {
       "id": 100,
       "name": "linkymclinkface",
       "link": "somelink.com"
    }
  }
]

It will result in a 204 code and the link created.
Note: If you GET the work item content, you will see that the response body may contain a different id (than the one specified unless it corresponds to the next one in the database).