Authentication with spring and web flux - spring

Question

I have a question concerning spring and web flux.
I have a spring project with spring security and MVC as dependencies.
This application accepts requests and check authentication using the session cookie.
For all the requests starting with "/api/" a failed authentication results in a 401 response, so that can be intercepted by the frontend as such.
For all the requests different from "/api/**" a failed authentication results in the server returning a login page so that the user can login.
This is the SecuritConfig class:
#Configuration
#EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
#Override
protected void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
.anyRequest()
.authenticated()
.and()
.formLogin()
.and()
.csrf()
.csrfTokenRepository(CookieCsrfTokenRepository.withHttpOnlyFalse())
.and()
.exceptionHandling()
.defaultAuthenticationEntryPointFor(new
HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED),
new AntPathRequestMatcher("/api/**"))
.and()
.cors();
}
}
Now, I am trying to achieve the same thing using web flux. With web flux the SecurityConfig is different, I can setup almost all the configs that I have in the old class but there is no equivalent for:
defaultAuthenticationEntryPointFor(new
HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED),
new AntPathRequestMatcher("/api/**"))
My new security config look like:
#Configuration
#EnableWebFluxSecurity
public class SecurityConfig {
#Bean
public SecurityWebFilterChain filterChain(ServerHttpSecurity http) {
return http
.authorizeExchange()
.pathMatchers("/login/**")
.permitAll()
.anyExchange()
.authenticated()
.and()
.formLogin()
.and()
.csrf()
.disable()
.exceptionHandling()
.authenticationEntryPoint(new
HttpStatusServerEntryPoint(HttpStatus.UNAUTHORIZED))
.and()
.build();
}
}
But in this case I only get 401 for all the requests that fail authentication.
Does anybody know how to achieve the same behavior with web flux?
Thank you