extension_ property
extension
May be used to represent additional information that is not
part of the basic definition of the element. To make the use of extensions
safe and manageable, there is a strict set of governance applied to the
definition and use of extensions. Though any implementer can define an
extension, there is a set of requirements that SHALL be met as part of the
definition of the extension.
Implementation
@JsonKey(name: 'extension')
List<FhirExtension>? get extension_ => throw _privateConstructorUsedError;