in scripts/lib/src/versions.dart [19:24]
Map<String, DartSdkVersion> versionsFromJson(
Map<String, dynamic> json, HttpRead read) {
var stable = DartSdkVersion.fromJson('stable', json['stable']!, read);
var beta = DartSdkVersion.fromJson('beta', json['beta']!, read);
return {'stable': stable, 'beta': beta};
}