code: private SLayer findOrAddSLayer(String name, SDocumentGraph graph)
    {
      List<SLayer> layerList = graph.getLayerByName(name);
      SLayer layer = (layerList != null && layerList.size() > 0)
        ? layerList.get(0) : null;
      if (layer == null)
      {
        layer = SaltFactory.createSLayer();
        layer.setName(name);
        graph.addLayer(layer);
      }
      return layer;
    }
docs: Retrieves an existing layer by it's name or creates and adds a new one if
  not existing yet
  
  @param name
  @param graph
  @return Either the old or the newly created layer