Protect Cockpit with SSO Keycloak

Hi there,

we try to protect the camunda cockpit with SSO (Keycloak). We already have seen the example (https://github.com/camunda-consulting/code/tree/master/snippets/springboot-security-sso) and tried to integrate it in our project.
We took the SpringSecurityAuthenticationProvider from the example and updated the SecurityConfig with our own.
Our SecurityConfig looks like:

http
            .cors().and()
            // disable csrf for api
            .csrf().disable()

            // authorize requests
            .authorizeRequests()

            // allow OPT for all requests (CORS)
            .antMatchers(HttpMethod.OPTIONS, "/**").permitAll()

            // exclude camunda routes from security
            .antMatchers(HttpMethod.GET, "/app/**").permitAll()
            .antMatchers(HttpMethod.PUT, "/app/**").permitAll()
            .antMatchers(HttpMethod.POST, "/app/**").permitAll()
            .antMatchers(HttpMethod.GET, "/lib/**").permitAll()
            .antMatchers(HttpMethod.PUT, "/lib/**").permitAll()
            .antMatchers(HttpMethod.POST, "/lib/**").permitAll()
            .antMatchers(HttpMethod.GET, "/api/**").permitAll()
            .antMatchers(HttpMethod.PUT, "/api/**").permitAll()
            .antMatchers(HttpMethod.POST, "/api/**").permitAll()

            // allow health checks
            .antMatchers(HttpMethod.GET, "/actuator/health").permitAll()
            .antMatchers(HttpMethod.GET, "/actuator/info").permitAll()

            // only allow authenticated users to call API
            .antMatchers(HttpMethod.GET, "/**").authenticated()
            .antMatchers(HttpMethod.PUT, "/**").authenticated()
            .antMatchers(HttpMethod.POST, "/**").authenticated()

            // whitelisting, everything else is denied
            .anyRequest().denyAll();

Unfortunately the SpringSecurityAuthenticationProvider is never used. Can anyone explain us how it works? Where exactly do we get the User from Keycloak? Do we need any further code?