there are 24 unique sequences of edges for the specific cube, i use 12 sequences and flip flop front with back for each of them
    static int R[][] = new int[][] {
        {1,2,3, 4,5, 6},
        {5,3,1, 4,2, 6},
        {2,1,5, 4,3, 6},
        {3,5,2, 4,1, 6},

        {6,4,3, 1,5, 2},
        {5,3,6, 1,4, 2},
        {4,6,5, 1,3, 2},
        {3,5,4, 1,6, 2},

        {1,2,6, 3,4, 5},
        {6,4,2, 3,1, 5},
        {2,1,4, 3,6, 5},
        {4,6,1, 3,2, 5}
    };
    static int front_back_rotate[][] = new int[][]{{0,1,2,3,4,5},{0,1,4,5,2,3}};
    //left right top  front bottom back
    //0       1     2    3     4      5
    static boolean eqv(int a[], int b[]) {
        for (int[] r: R) {
            for (int[] I: front_back_rotate) {
                int front_back[] = new int[6];
                for (int i=0; i<6; i++) {
                    front_back[r[I[i]]-1] = a[i];
                }
                if (Arrays.equals(front_back, b)) return true;
            }
        }
        return false;
    }

You don't need to try all rotation combinations. Just rotate left and rotate down, use recursion and all combinations will be generated easily.