go_oop3.java

public class Human {
  public String name;
  
  public Human(String name) {
    this.name = name;
  }
}

public class Student {
  private Human human;
  private int id;
  
  public Student(Human human, int id) {
    this.human = human;
    this.id = id;
  }
}

public static void main(String[] args) {
  Human h = new Human("foo");
  Student s = new Student(h, 1);
  // changing the Human object which is supposed to be private.
  h.name = "bar";
}