Given a list of integers and a window size k, find the maximum value in each sliding window of size k as it moves from left to right across the list. Each window contains k consecutive elements, and the window slides one position at a time. Return a list of maximum values, one for each window position. Return an empty list for null or empty input, or when k is less than 1.

If k is greater than the list size, treat the entire list as a single window and return the maximum of all elements.

Method signature: public static List<Integer> slidingWindowMax(List<Integer> nums, Integer k)

Examples:

Input: nums = [1, 3, -1, -3, 5, 3, 6, 7], k = 3 Output: [3, 3, 5, 5, 6, 7] Explanation: Window [1,3,-1]=3, [3,-1,-3]=3, [-1,-3,5]=5, [-3,5,3]=5, [5,3,6]=6, [3,6,7]=7 Input: nums = [1, 2, 3], k = 1 Output: [1, 2, 3] Explanation: Each element is its own window Input: nums = [4, 2, 7], k = 3 Output: [7] Explanation: Only one window spans the entire list Input: nums = [5, 5, 5, 5], k = 2 Output: [5, 5, 5] Explanation: All values are the same, each window maximum is 5
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