code: public Map<SNode, Long> getMarkedAndCovered()
    {
      if(cachedMarkedAndCoveredNodes == null)
      {      
        if (document != null)
        {
          cachedMarkedAndCoveredNodes = CommonHelper.createSNodeMapFromIDs(
            markedAndCovered, document.getDocumentGraph());
        }
      }
      
      return cachedMarkedAndCoveredNodes;
    }
docs: This map is used for calculating the colors of a matching node.
  
  All Nodes, which are not included, should not be colorized. For getting
  HEX-values according to html or css standards, it is possible to use
  {@link MatchedNodeColors}.
  
  @return