@Value.Default
    public Gson gson() {
      GsonBuilder gsonBuilder = new GsonBuilder();
      for (TypeAdapterFactory factory : ServiceLoader.load(TypeAdapterFactory.class)) {
        gsonBuilder.registerTypeAdapterFactory(factory);
      }
      return gsonBuilder.create();
    }
the fully configured gson instance.
@return the gson instanse
gson/src/org/immutables/gson/stream/GsonMessageBodyProvider.java