docs: private void addSecondaryLayer() {
      LineLayer secondary = TrafficLayer.getLineLayer(
        Secondary.BASE_LAYER_ID,
        Secondary.ZOOM_LEVEL,
        Secondary.FILTER,
        Secondary.FUNCTION_LINE_COLOR,
        Secondary.FUNCTION_LINE_WIDTH,
        Secondary.FUNCTION_LINE_OFFSET
      );
  
      LineLayer secondaryCase = TrafficLayer.getLineLayer(
        Secondary.CASE_LAYER_ID,
        Secondary.ZOOM_LEVEL,
        Secondary.FILTER,
        Secondary.FUNCTION_LINE_COLOR_CASE,
        Secondary.FUNCTION_LINE_WIDTH_CASE,
        Secondary.FUNCTION_LINE_OFFSET,
        Secondary.FUNCTION_LINE_OPACITY_CASE
      );
  
      addTrafficLayersToMap(secondaryCase, secondary, getLastAddedLayerId());
    }