Adding China to a round the world ticket

I am leaving on a round the world trip soon and have flights booked to and from various locations but have recently decided to add China to my intinerary. I am visiting a friend in Hong Kong before flying into Shanghai and then intend to some travelling in China either with internal flights or train travel.
Do I need to provide details of a flight leaving China or does the fact that I have onward flights booked on my intinerary suffice ?