decode static method Null safety

Implementation

static LocationIndicatorLayer decode(String properties) {
  var map = json.decode(properties);
  if (map["layout"] == null) {
    map["layout"] = {};
  }
  if (map["paint"] == null) {
    map["paint"] = {};
  }
  return LocationIndicatorLayer(
    id: map["id"],
    minZoom: map["minzoom"]?.toDouble(),
    maxZoom: map["maxzoom"]?.toDouble(),
    visibility: map["layout"]["visibility"] == null
        ? Visibility.VISIBLE
        : Visibility.values.firstWhere((e) => e
            .toString()
            .split('.')
            .last
            .toLowerCase()
            .contains(map["layout"]["visibility"])),
    bearingImage: map["layout"]["bearing-image"],
    shadowImage: map["layout"]["shadow-image"],
    topImage: map["layout"]["top-image"],
    accuracyRadius: map["paint"]["accuracy-radius"]?.toDouble(),
    accuracyRadiusBorderColor:
        (map["paint"]["accuracy-radius-border-color"] as List?)?.toRGBAInt(),
    accuracyRadiusColor:
        (map["paint"]["accuracy-radius-color"] as List?)?.toRGBAInt(),
    bearing: map["paint"]["bearing"]?.toDouble(),
    bearingImageSize: map["paint"]["bearing-image-size"]?.toDouble(),
    emphasisCircleColor:
        (map["paint"]["emphasis-circle-color"] as List?)?.toRGBAInt(),
    emphasisCircleRadius: map["paint"]["emphasis-circle-radius"]?.toDouble(),
    imagePitchDisplacement:
        map["paint"]["image-pitch-displacement"]?.toDouble(),
    location: (map["paint"]["location"] as List?)
        ?.map<double?>((e) => e.toDouble())
        .toList(),
    perspectiveCompensation:
        map["paint"]["perspective-compensation"]?.toDouble(),
    shadowImageSize: map["paint"]["shadow-image-size"]?.toDouble(),
    topImageSize: map["paint"]["top-image-size"]?.toDouble(),
  );
}