url property
URL is the row's external anchor — its extRef — which is a link only when the feeder sent one. A mirrored GitHub issue carries "github:owner/repo#123" and an agent's PR row carries the pushed branch. Empty for a row opened here.
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? url;