Object-Oriented Programming in Java (OOP Concepts)

Given:

public class Box {
    int size;

    Box(int s) {
        size = s;
    }
}

class Laser {
    public static void main(String[] args) {
        Box b1 = new Box(5);
        Box[] ba = go(b1, new Box(6));
        ba[0] = b1;
        for (Box b : ba) System.out.print(b.size + " ");
    }

    static Box[] go(Box b1, Box b2) {
        b1.size = 4;
        Box[] ma = {b2, b1};
        return ma;
    }
}

What is the result?