code: protected Map<String, String> getGroupMap(final DocWorkUnit workUnit) {
          Map<String, String> propertyMap = new HashMap<>();
          propertyMap.put("id", getGroupIdFromName(workUnit.getGroupName()));
          propertyMap.put("name", workUnit.getGroupName());
          propertyMap.put("summary", workUnit.getGroupSummary());
          return propertyMap;
      }
docs: Helper routine that returns the map of group name and summary given the workUnit. Subclasses that
  override this should call this method before doing further processing.
  
  @param workUnit
  @return The property map for the work unit's entry in the index map for this doclet.