code: private Map getMap()
      {
          if (_map != null)
              return _map;
  
          synchronized (this) {
              if (_map != null)
                  return _map;
              _map = new HashMap();
          }
          return _map;
      }
docs: **************************************** End Map Interface **********************************************
  
  
  This method will return the map.  If the map hasn't been created
  it will be created.  This is done in a thread safe way.
  @return the map implementation.