code: public synchronized void authConnection(MemcachedConnection conn,
        OperationFactory opFact, AuthDescriptor authDescriptor,
        MemcachedNode node) {
      interruptOldAuth(node);
      AuthThread newSASLAuthenticator =
          new AuthThread(conn, opFact, authDescriptor, node);
      nodeMap.put(node, newSASLAuthenticator);
    }
docs: Authenticate a new connection. This is typically used by a MemcachedNode in
  order to authenticate a connection right after it has been established.
  
  If an old, but not yet completed authentication exists this will stop it in
  order to create a new authentication attempt.
  
  @param conn
  @param opFact
  @param authDescriptor
  @param node