Summary

Unable to add more than 1 issue link when creating/editing an issue via REST API

Steps to Reproduce

1. Run PUT /rest/api/2/issue/{issueIdOrKey} with the following JSON data

   {
      "update":{
         "issuelinks":[
            {
               "add":{
                  "type":{
                     "name":"Blocks",
                     "inward":"is blocked by",
                     "outward":"blocks"
                  },
                  "outwardIssue":{
                     "key":"TEST-1"
                  }
               }
            },
            {
               "add":{
                  "type":{
                     "name":"Blocks",
                     "inward":"is blocked by",
                     "outward":"blocks"
                  },
                  "outwardIssue":{
                     "key":"TEST-2"
                  }
               }
            }
         ]
      }
   }

Expected Results

Issue is updated with 2 issue links

Actual Results

Following is seen as response

{
    "errorMessages": [],
    "errors": {
        "issuelinks": "Too many operations (2) provided for field 'issuelinks'. We support at most 1 operation for this field."
    }
}

Notes

AFAICT there is no reason for this limitation. You can create multiple issue links and you can add multiple labels for example using a similar JSON as the above since it's an array.

Workaround

Add issue links one at a time using multiple REST calls.