subject property
Subject is the identity within that kind — whose row this is. Every row of one subject is in ONE split, decided by that subject's earliest instant, so a subject is never on both sides of a cut.
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? subject;