Relationship between Student (is-a) Person and relationship Group (has-a) Student?

Question

Java

public class Student extends Person{ 
Group group;
}

public class Group{ 
Student student;
}

Answer 1

Yes

public class Student{
Group group;
}

just what the hell is this, why are there two Student classes

Answer 2

Good afternoon.
Student is a Person is an association.
Group has a Person is an aggregation. It is not a composition, since a student can exist separately from the group.
https://habr.com/ru/post/150041/
https://javarush.ru/groups/posts/1967-otnoshenija-...
https://habr.com/ru/post/511798/