Не проходит валидация.

package com.javarush.task.task08.task0824; import java.util.ArrayList; /* Собираем семейство */ public class Solution { public static void main(String[] args) { Human child1 = new Human("child1", false, 15); Human child2 = new Human("child2", false, 12); Human child3 = new Human("child3", false, 17); ArrayList<Human> children1 = new ArrayList<Human>(); children1.add(child1); children1.add(child2); children1.add(child3); Human father = new Human("peter", true, 40, children1); ArrayList<Human> children2 = new ArrayList<Human>(); children2.add(father); Human mother = new Human("lois", false, 40, children1); ArrayList<Human> children3 = new ArrayList<Human>(); children3.add(mother); Human ded1 = new Human("ded1", true, 78, children2); Human babka1 = new Human("babka1", false, 78, children2); Human ded2 = new Human("ded2", true, 78, children3); Human babka2 = new Human("babka2", false, 78, children3); System.out.println(ded1); System.out.println(babka1); System.out.println(ded2); System.out.println(babka2); System.out.println(mother); System.out.println(father); System.out.println(child1); System.out.println(child2); System.out.println(child3); } public static class Human { String name; boolean sex; int age; ArrayList<Human> children; public Human(String name, boolean sex, int age) { this.name = name; this.sex = sex; this.age = age; } public Human(String name, boolean sex, int age, ArrayList<Human> children) { this.name = name; this.sex = sex; this.age = age; this.children = children; } public String toString() { String text = ""; text += "Имя: " + this.name; text += ", пол: " + (this.sex ? "мужской" : "женский"); text += ", возраст: " + this.age; int childCount = 0; if (children != null) { childCount = this.children.size(); } if (childCount > 0) { text += ", дети: " + this.children.get(0).name; } return text; } } }