Где ошибка?

package com.javarush.task.task21.task2106; import java.util.Date; import java.util.HashSet; import java.util.Set; /* Ошибка в equals/hashCode */ public class Solution { private int anInt; private String string; private double aDouble; private Date date; private Solution solution; public Solution(int anInt, String string, double aDouble, Date date, Solution solution) { this.anInt = anInt; this.string = string; this.aDouble = aDouble; this.date = date; this.solution = solution; } @Override public boolean equals(Object o) { if (this == o) return true; if (!(o instanceof Solution)) return false; Solution solution1 = (Solution) o; boolean firstBool = (aDouble == solution1.aDouble); boolean secondBool = (anInt == solution1.anInt); boolean thirdBool = (solution1.date != null && this.date != null && date.equals(solution1.date)); boolean foursBool = (solution1.solution != null && this.solution != null && solution.equals(solution1.solution)); boolean fifthBool = (solution1.string != null && this.string != null && string.equals(solution1.string)); return firstBool && secondBool && thirdBool && foursBool && fifthBool; } @Override public int hashCode() { int result; long temp; result = anInt; temp = aDouble != +0.0d ? Double.doubleToLongBits(aDouble) : 0L; result = 31 * result + (int) (temp ^ (temp >>> 32)); result = 31 * result + (solution != null ? solution.hashCode() : 0); return result; } public static void main(String[] args) { // Date date = new Date(); // System.out.println(new Solution(0, "", 0d, date, null) // .equals(new Solution(0, "", 0d, date, null))); } }