public class Solution {
    public int[][] groupConsecutiveDuplicates(int[] nums) {
        if (nums == null || nums.length == 0) { 
            return new int[0][];    
        }

        List<int[]> groups = new ArrayList<>();
        int count = 1;
        int currentNumber = nums[0];

        for (int i = 1; i < nums.length; i ++) {
            int number = nums[i];
            if (number == currentNumber) {
                count++;
            } else {
                groups.add(createGroup(currentNumber, count));
                count = 1;
                currentNumber = number;
            }
        }

        groups.add(createGroup(currentNumber, count));

        return groups.toArray(new int[groups.size()][]);
    }

    private int[] createGroup(int number, int count) {
        int[] group = new int[count];

        for (int i = 0; i < group.length; i++) {
            group[i] = number;
        }

        return group;
    }
}