Как работает Arrays.binarySearch

package com.javarush.task.task12.task1233;

/*
Изоморфы наступают
*/

import java.util.Arrays;

public class Solution {
    public static void main(String[] args) throws Exception {
        int[] data = new int[]{1, 2, 3, 5, -2, -8, 0, 77, 5, 5};

        Pair<Integer, Integer> result = getMinimumAndIndex(data);

        System.out.println("Minimum is " + result.x);
        System.out.println("Index of minimum element is " + result.y);
    }

    public static Pair<Integer, Integer> getMinimumAndIndex(int[] array) {
        if (array == null || array.length == 0) {
            return new Pair<Integer, Integer>(null, null);
        }
        int[] copy = array.clone();
        Arrays.sort(copy);
        return new Pair<Integer, Integer>(copy[0], Arrays.binarySearch(array,copy[0]));
    }


    public static class Pair<X, Y> {
        public X x;
        public Y y;

        public Pair(X x, Y y) {
            this.x = x;
            this.y = y;
        }
    }
}