Changing resources

A PATCH body is a JSON merge patch (RFC 7396), sent as application/json. Send only what should change — never the whole resource. Every field carries one of three meanings:

The field is	Meaning
omitted	leave it as it is
null	clear it
a value	set it to that value

{"assigneeId": 17, "priorityName": null}

That assigns the ticket and clears its priority. Everything else keeps its current value, so there is no read-modify-write cycle and no risk of writing back a field you never meant to touch.

Rules worth knowing:

• A relation is changed through the scalar that identifies it — assigneeId, statusName, typeName — never by embedding the related object. A nested assignee object in the body is ignored.
• An array replaces the whole collection. Merge patch does not merge arrays: {"labels":["billing"]} leaves exactly one label, and both {"labels":null} and {"labels":[]} remove all of them. A label name that does not exist yet is created.
• A field that cannot be empty has no null form. statusName and subject are always set, so an explicit null there leaves the current value unchanged instead of clearing it.
• A status change is validated against the configured transitions and answered with 400 when the transition is not permitted.
• The response carries the patched resource under data.