code: @NonNull
    public String toJson() {
      Gson gson = new GsonBuilder()
        .registerTypeAdapterFactory(GeometryAdapterFactory.create())
        .registerTypeAdapter(BoundingBox.class, new BoundingBoxTypeAdapter())
        .registerTypeAdapterFactory(GeocodingAdapterFactory.create())
        .create();
      return gson.toJson(this, GeocodingResponse.class);
    }
docs: This takes the currently defined values found inside this instance and converts it to a GeoJson
  string.
  
  @return a JSON string which represents this Geocoding Response
  @since 1.0.0