enum generates nullable values

[stuartmorgan]

I have this Java declaration in a class:

  public enum StreamingFormat {
    /** Default, if the format is either not known or not another valid format. */
    UNKNOWN,

    /** Smooth Streaming. */
    SMOOTH,

    /** MPEG-DASH (Dynamic Adaptive over HTTP). */
    DYNAMIC_ADAPTIVE,

    /** HTTP Live Streaming (HLS). */
    HTTP_LIVE
  }

The resulting generated code is a class with getters like:

  static VideoAsset$StreamingFormat? get DYNAMIC_ADAPTIVE =>
      _id_DYNAMIC_ADAPTIVE.get(
          _class, const $VideoAsset$StreamingFormat$NullableType());

I would not expect enum values to be nullable. (It also not clear to me why they are a class in the first place, rather than an enum.)