SpEL Cannot resolve variable

I tried to use SpEL to pass a userId parameter in an mvcMatchers method to an access() method.
This is based on the tutorial Spring Security 4.1 and Beyond

@Override
protected void configure(HttpSecurity http) throws Exception {
    http.csrf()
            .disable()
        .authorizeRequests()
            .mvcMatchers(HttpMethod.GET, "/", "/home").permitAll()
            .mvcMatchers("/users/{userId}").access("@authz.check(#userId,principal)")
            .mvcMatchers(HttpMethod.POST, SIGN_UP_URL).permitAll()
            .mvcMatchers("/admin").denyAll()
            .anyRequest().authenticated()
            .and()
        .logout().permitAll()
            .and()
        .addFilter(new JWTAuthenticationFilter(authenticationManager()))
        .addFilter(new JWTAuthorizationFilter(authenticationManager()));
}

As I understood {userId} in mvcMatchers() should become a variable, which can be passed to access.

This way throws an exception: Cannot resolve variable userId.

I am fairly new to Spring (Boot) and completely new to SpEL.

I hope someone can help me out here.