Link this issue to another

Idempotent. The same pair and type returns the existing row with created false and writes nothing. blocked_by is stored as blocks with the two ids swapped. related is stored with the lower id as the source so asking from either issue is the same row. Both issues must be in this issue's team. A blocks link that would close a loop is refused, and so is a duplicate link that would loop back on itself. An issue can be a duplicate of only one other issue.

curl -X POST "https://example.com/v1/issues/497f6eca-6276-4993-bfeb-53cbbbba6f08/relations" \  -H "Content-Type: application/json" \  -d '{    "relatedIssueId": "ebbf942a-e010-40d7-b2c5-c48aa1370861",    "type": "blocks"  }'

{  "relation": {    "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",    "type": "blocks",    "issueId": "96179c34-d541-49af-b046-c06f0377732c",    "relatedIssueId": "ebbf942a-e010-40d7-b2c5-c48aa1370861"  },  "created": true}