code: private Category searchCategory(String breadcrumb) {
      return model.getFlatCategoriesLst().stream().filter(
          cat -> cat.getBreadcrumb().equals(breadcrumb)
      ).findAny().orElse(null);
    }
docs: Searches in all categories for the category that matches a breadcrumb.
  
  @param breadcrumb the breadcrumb, which the matching category should have
  @return a matching category or null if nothing is found