If your worried about whether or not it will be done, then talk with your contractor. I'm shure they will do it if you mention it to him/her. Otherwise, you could just buy some Z flashing, caulk & roofing nails and install it yourself. Just put a bead of caulk about an inch down from the top of the flashed surface, tuck the flashing up behind the drip edge or layer of siding, nail it in place and apply finishing trim.
lol -
almost sounds like I know what I'm talking about .....