Spring boot - basic auth and X.509 certificate authentication

Question

Can basic auth be used in conjunction with X.509 certificate mutual authentication in a spring boot 2 app?

In my WebSecurityConfig I have this:

protected void configure(HttpSecurity http) throws Exception {

    http.authorizeRequests()
      .anyRequest().authenticated()
      .and()
      .httpBasic()
      .and()
      .x509();
  }

I supply the client certificate via postman and include the basic authorization username and password. I get a successful response.

When I remove the basic auth username and password I still get a successful response when I would have expected an error... ~ so guessing basic auth gets ignored when x509 is specified?

Thanks,