>>>
class VeryInterestingThing {
  factory VeryInterestingThing.fromJson(
        mylibrarythathasalongname.JsonData jsonData) => new VeryInterestingThing(
        otherlibrary.InterestingState.fromJson(jsonData.encodedState));
}
<<<
class VeryInterestingThing {
  factory VeryInterestingThing.fromJson(
    mylibrarythathasalongname.JsonData jsonData,
  ) => new VeryInterestingThing(
    otherlibrary.InterestingState.fromJson(jsonData.encodedState),
  );
}