It already works in the typical case where the main application class is also the class that's annotated with @SpringBootApplication. However, it fails when the two are separated like this:

package com.example.demonativesample;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.SpringApplication;
import org.springframework.context.annotation.Bean;

public class DemoNativeSampleApplication {

    public static void main(String[] args) {
        SpringApplication.run(SeparateConfigurationClass.class, args);
    }

    @SpringBootApplication
    static class SeparateConfigurationClass {

        @Bean
        public String one() {
            return "one";
        }

    }

}