docs: public Collection values()
      {
          if (values != null) return values;
          values = new AbstractCollection()
          {
              public int size()
              {
                  return size;
              }
  
              public void clear()
              {
                  ReferenceMap.this.clear();
              }
  
              public Iterator iterator()
              {
                  return new ValueIterator();
              }
          };
          return values;
      }