Spring-Boot REST service basic http auth exclude one endpoint

I have a REST-only micro service built on Spring-Boot version 1.5.4.RELEASE with spring-boot-starter-security. The service has no web pages, just JSON in and out. The username and password are configured in the application.properties file. With credit to http://ryanjbaxter.com/2015/01/06/securing-rest-apis-with-spring-boot/ the following configuration causes the server to implement basic HTTP authentication quite nicely, it accepts the credentials and rejects unauthorized requests:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

@Configuration
public class SecurityConfiguration extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable().authorizeRequests() //
                .anyRequest().authenticated().and().httpBasic();        
    }
}

My question is that I'd like to exclude one little ole path, one tiny endpoint, from basic HTTP authentication. From frantic googling and SO copy-pasting I revised the above to have this:

    http.csrf().disable().authorizeRequests() //
        .antMatchers("/healthcheck").permitAll()
        .anyRequest().authenticated().and().httpBasic();

This compiles and runs without warning, but that path is not opened for unauthenticated access. I still must supply credentials to check the service health.

Do I have to match paths one by one? My little healthcheck endpoint is at the base of the context path, as are a whole bunch of others - adding paths one-by-one would be a hassle.

The relevant part of my application.properties file is:

security.user.name = web-user
security.user.password = web-pass
management.security.roles=SUPERUSER

Maybe I need to fiddle roles somehow?

Please help, thanks in advance.

Update 1:

Path information - I'd like this path (and many more at root) to be guarded:

localhost:8081/abcd/user

And I'd like ONLY this one path to be open, no auth required:

localhost:8081/abcd/healthcheck

Update 2: Looks like I largely duplicated this 3-year-old question, but no answer was accepted there for my issue:

spring-boot setup basic auth on a single web app path?