extRef property
ExtRef anchors the item to something outside the todo — a mirrored issue ("github:owner/repo#123"), a pushed PR branch, or a record on another plane. It is the idempotency key the mirror upsert matches on. Absent when the item has no external origin.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
String? extRef;