You can hit the CFRP with a sledge hammer and it will just bounce off.
Hit it with something heavy doing more than 2 mph and you're in trouble. The damage is not visible. A small NDT ultra sound go-nogo device has to be used and if necessary access to the area immediatly behind the impact point to check delamination.
At least one 787 customer has had the honour of a major repair after a catering truck put an L shaped hole in the fuselage.
All very hush hush.