code: function addNewLayersToSplitMap(splitMaps, layers) {
    const newLayers = Array.isArray(layers) ? layers : [layers];
  
    if (!splitMaps || !splitMaps.length || !newLayers.length) {
      return splitMaps;
    }
  
    // add new layer to both maps,
    //  don't override, if layer.id is already in splitMaps.settings.layers
    return splitMaps.map(settings => ({
      ...settings,
      layers: {
        ...settings.layers,
        ...newLayers.reduce(
          (accu, newLayer) =>
            newLayer.config.isVisible
              ? {
                  ...accu,
                  [newLayer.id]: settings.layers[newLayer.id]
                    ? settings.layers[newLayer.id]
                    : generateLayerMetaForSplitViews(newLayer)
                }
              : accu,
          {}
        )
      }
    }));
  }
docs: Add new layers to both existing maps
  @param {Object} splitMaps
  @param {Object|Array<Object>} layers
  @returns {Array<Object>} new splitMaps