docs: public boolean contains(Object value) {
      if (value == null) {
        throw new NullPointerException();
      }
  
      FastHashtableEntry tab[] = table;
      for (int i = tab.length ; i-- > 0 ;) {
        for (FastHashtableEntry e = tab[i] ; e != null ; e = e.next) {
          if (e.value.equals(value)) {
            return true;
          }
        }
      }
      return false;
    }