actor property
Actor is who produced the turn. Empty takes the validated caller, which is what an agent writing its own transcript wants; naming one is for a surface recording on somebody else's behalf.
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? actor;