userId property
UserID attributes the run inside the caller's org. It is a label, never a tenant: the org is resolved from the validated principal and a value here cannot widen what the run may reach.
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? userId;