code: public Category loadSelectedCategory() {
      String breadcrumb = storageHandler.loadSelectedCategory();
      Category defaultCategory = getCategories().get(DEFAULT_CATEGORY);
      if (breadcrumb == null) {
        return defaultCategory;
      }
      return flatCategoriesLst.stream()
          .filter(category -> category.getBreadcrumb().equals(breadcrumb))
          .findAny().orElse(defaultCategory);
    }
docs: Loads the last selected Category before exiting the Preferences window.
  
  @return last selected Category