Missing GoalAchievementStatus code system

The [`GoalAchievementStatus`](https://www.hl7.org/fhir/codesystem-goal-achievement.html) code system is defined as part of R4 and is the preferred binding for the [`Goal.achievementStatus`](https://www.hl7.org/fhir/goal-definitions.html#Goal.achievementStatus) element. However, no protos are generated for it in this repo.

The JSON spec **IS** included in the repo here:
https://github.com/google/fhir/blob/bc3fe21af307a0a8c4cca00bb24995137ee9a683/spec/hl7.fhir.core/4.0.1/package/CodeSystem-goal-achievement.json#L1

Other Goal code systems are properly included, e.g. `GoalLifecycleStatusCode`:
https://github.com/google/fhir/blob/bc3fe21af307a0a8c4cca00bb24995137ee9a683/proto/google/fhir/proto/r4/core/codes.proto#L1894-L1896

Another idea I had was that maybe this code system maturity was below some kind of filter used in this repo. It is considered `0 - Draft` so that may make sense. However, the `GoalAcceptanceState` code system is also `0 - Draft` and it is included:
https://github.com/google/fhir/blob/bc3fe21af307a0a8c4cca00bb24995137ee9a683/proto/google/fhir/proto/r4/core/codes.proto#L1880-L1882

**Does anyone know if this was intentional or a bug?**