code: public void signin(String username, String password) {
  		logger.debug("signin:" + username);
  
  		Authentication request = new UsernamePasswordAuthenticationToken(username, password, null);
  		SecurityContextHolder.getContext().setAuthentication(request);
  	}
docs: WARNING: Normally this is used by non-web interface. For web interface,
  pls use Spring Security config to auto authenticate Here there is no
  authenticate
  
  @param username
  @param password