Write a method called fillGaps that accepts a PriorityQueue of integers as a parameter and adds elements to it until every element in its range of smallest to largest is represented once if it was not previously found in the priority queue. For example, if the queue stores [1, 3, 3, 6, 6, 8], your method should modify the queue to store [1, 2, 3, 3, 4, 5, 6, 6, 7, 8]. You may use one collection as auxiliary storage.