code: public Category getCategory(int pageId) {
          long hibernateId = __getCategoryHibernateId(pageId);
          if (hibernateId == -1) {
              return null;
          }
  
          try {
              Category cat = new Category(this, hibernateId);
              return cat;
          } catch (WikiPageNotFoundException e) {
              return null;
          }
      }
docs: Gets the category for a given pageId.
  @param pageId The id of the {@link Category}.
  @return The category object or null if no category with this pageId exists.