toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
if (predicateType != null) 'predicateType': predicateType!,
if (provenance != null) 'provenance': provenance!.toJson(),
if (subject != null)
'subject': subject!.map((value) => value.toJson()).toList(),
if (type != null) 'type': type!,
};