horizon property
Horizon is the maturity horizon these counts were measured under, IN DAYS — the caller's, or 120. It decides Matured (an event is matured when its at plus this many days is not after now), it sets each event's own as-of and so which assertions were visible to it, and when the caller bounds nothing it also places the default window's end.
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? horizon;