Java8流groupingBy。如果只有一个分组值的对象，如何设置字段？

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        // 示例数据
        List<Person> persons = Arrays.asList(
                new Person("Alice", 25),
                new Person("Bob", 30),
                new Person("Charlie", 25)
        );

        // 根据年龄分组，并设置字段为姓名
        Map<Integer, String> ageToNameMap = persons.stream()
                .collect(Collectors.groupingBy(Person::getAge,
                        Collectors.toMap(person -> person.getAge(), person -> person.getName())));

        // 输出结果
        ageToNameMap.forEach((age, name) -> System.out.println("Age: " + age + ", Name: " + name));
    }

    static class Person {
        private String name;
        private int age;

        public Person(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public int getAge() {
            return age;
        }
    }
}