Dynamic, optional collections of beans in Spring Java `@Configuration` classes

DemoApplication.java

package demo;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
    
    /*
    @Bean
    Foo a() {
        return new Foo("a");
    }

    @Bean
    Foo b() {
        return new Foo("b");
    }
    */

    @Bean
    InitializingBean bar(Optional<List<Foo>> fooList) {
        return () -> {
            System.out.println("fooList.size = " + fooList.map(List::size).orElse(0));
            System.out.println("foos.size = " + this.foos.size());
            System.out.println("optionalFoos.size = " + this.optionalFoos.map(List::size).orElse(0));
        };
    }

    @Autowired(required = false)
    private List<Foo> foos = new ArrayList<>();

    @Autowired
    private Optional<List<Foo>> optionalFoos;
    
}


class Foo {

    private final String name;

    @Override
    public String toString() {
        return "Foo{" +
                "name='" + name + '\'' +
                '}';
    }

    public Foo(String name) {
        this.name = name;
    }
}