docs: public static int calculateCategoryIDs(DoubleLinkedPoiCategory rootNode, int maxValue) {
          int newMax = maxValue;
          for (PoiCategory c : rootNode.childCategories) {
              newMax = calculateCategoryIDs((DoubleLinkedPoiCategory) c, newMax);
          }
  
          rootNode.id = newMax;
  
          return newMax + 1;
      }