docs: private void addTrunkLayer() {
      LineLayer trunk = TrafficLayer.getLineLayer(
        Trunk.BASE_LAYER_ID,
        Trunk.ZOOM_LEVEL,
        Trunk.FILTER,
        Trunk.FUNCTION_LINE_COLOR,
        Trunk.FUNCTION_LINE_WIDTH,
        Trunk.FUNCTION_LINE_OFFSET
      );
  
      LineLayer trunkCase = TrafficLayer.getLineLayer(
        Trunk.CASE_LAYER_ID,
        Trunk.ZOOM_LEVEL,
        Trunk.FILTER,
        Trunk.FUNCTION_LINE_COLOR_CASE,
        Trunk.FUNCTION_LINE_WIDTH_CASE,
        Trunk.FUNCTION_LINE_OFFSET
      );
  
      addTrafficLayersToMap(trunkCase, trunk, getLastAddedLayerId());
    }