Optional__kindDiscriminator kind, written on serialization (SohlEntity.toJSON) and read back on revival. Optional as constructor input — it is derived from the concrete class, not supplied by callers.
Short abbreviation for the delta's source.
Localization key naming the delta's source (see ValueDelta.label).
The operator selecting how the delta combines with the value.
The delta's value (numeric, or a boolean flag).
Construction data for a ValueDelta.