code: @Override
  	protected void configure(AuthenticationManagerBuilder auth) throws Exception {
  		OpenIDAuthenticationProvider openidProvider = new OpenIDAuthenticationProvider();
  		openidProvider.setAuthenticationUserDetailsService(new SimpleUserService());
  		auth.authenticationProvider(openidProvider);
  
  		RememberMeAuthenticationProvider rmeProvider = new RememberMeAuthenticationProvider(Config.APP_SECRET_KEY);
  		auth.authenticationProvider(rmeProvider);
  
  		JWTAuthenticationProvider jwtProvider = new JWTAuthenticationProvider();
  		auth.authenticationProvider(jwtProvider);
  
  		LDAPAuthenticationProvider ldapProvider = new LDAPAuthenticationProvider();
  		auth.authenticationProvider(ldapProvider);
  	}
docs: Configures the authentication providers.
  
  @param auth a builder
  @throws Exception ex