Find pair from Sorted Array

FindPair

//Time complexity O(N), Space Complexity O(1)
    public static List<Pair<Integer, Integer>> getPairs(int[] array, final int sum){
        int start = 0;
        int end = array.length-1;
        List<Pair<Integer, Integer>> list = new ArrayList<>();
        while (start < end){
            int resultSum = array[start] + array[end];
            if(resultSum < sum){
                start++;
            }else if (resultSum > sum){
                end --;
            }else{
                list.add(Pair.of(array[start], array[end]));
                start ++ ;
                end --;
            }

        }
        return list;
    }

PairArray

package org.idey.algo.ds;

import java.util.Map;

public interface Pair<K,V> extends Map.Entry<K,V> {
    @Override
    default  V setValue(V value) {
        throw new UnsupportedOperationException("Invalid operation");
    }

    static <K,V> Pair<K,V> of(K key, V value) {
        return new PairImpl<>(key,value);
    }

    class PairImpl<K,V> implements Pair<K,V>{
        private K key;
        private V value;

        private PairImpl(K key, V value) {
            this.key = key;
            this.value = value;
        }

        @Override
        public K getKey() {
            return key;
        }

        @Override
        public V getValue() {
            return value;
        }
    }
}