unmatured property
Unmatured is how many events in the window have NOT aged past the horizon. They are not unlabelled — they are not yet askable, and a supervised set must exclude them rather than treat them as negatives. Matured + Unmatured is Events.
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
int? unmatured;