double distance = 6.0D;
Block eye = player.getTargetBlock(null, (int)distance + 1);
if (!StopCheckUtils.compare(eye, block)) {
    event.setCancelled(true);
}

public static boolean compare(Block b, Block b2) {
    int x = b.getX(); int x2 = b2.getX();
    int y = b.getY(); int y2 = b2.getY();
    int z = b.getZ(); int z2 = b2.getZ();

    if ((x == x2) && (y == y2) && (z == z2)) {
        return true;
    } else {
        return false;
    }
}