docs: public String hiddenToEncodedString() {
          StringBuilder buf = new StringBuilder();
          // Encode hidden bug categories
          for (Iterator<String> i = hiddenBugCategorySet.iterator(); i.hasNext();) {
              buf.append(i.next());
              if (i.hasNext()) {
                  buf.append(LISTITEM_DELIMITER);
              }
          }
          buf.append(FIELD_DELIMITER);
  
          return buf.toString();
      }