The longest diagonals of a square matrix are defined as follows: - The first longest diagonal goes from the top-left corner to the bottom-right corner. - The second longest diagonal goes from the top-right corner to the bottom-left corner. Given a square matrix, your task is to swap its longest diagonals by exchanging their elements at the corresponding positions. Example: matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]