Disable creating a default user with random password in Spring, see more in https://blog.gypsyengineer.com/en/security/tips-configuring-security-rest-api-spring.html

SecurityConfig.java

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    // ...

    @Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }
}