code: public Collection<String> getBugCategories() {
          ArrayList<String> result = new ArrayList<>(categoryDescriptionMap.size());
          for(BugCategory c : categoryDescriptionMap.values()) {
              if (!c.isHidden()) {
                  result.add(c.getCategory());
              }
          }
          return result;
      }
docs: Get a Collection containing all known bug category keys. E.g.,
  "CORRECTNESS", "MT_CORRECTNESS", "PERFORMANCE", etc.
  
  Excludes hidden bug categories
  
  @return Collection of bug category keys.