Identifier constructor
Creates a new Identifier instance.
Implementation
Identifier({
Type? type,
Uri? system,
String? value,
String? use,
}) : this.fromJson(
JsonObject({
if (type != null) typeField.name: type.json,
if (system != null) systemField.name: JsonString(system.toString()),
if (value != null) valueField.name: JsonString(value),
if (use != null) useField.name: JsonString(use),
}),
);