code: public static synchronized HashManager getInstanceFor(XMPPConnection connection) {
          HashManager hashManager = INSTANCES.get(connection);
          if (hashManager == null) {
              hashManager = new HashManager(connection);
              INSTANCES.put(connection, hashManager);
          }
          return hashManager;
      }
docs: Get an instance of the HashManager for the  given connection.
  @param connection
  @return the manager for the given connection.