Question regarding visa documents for invitation letter issued by government Authority.

Hey,

So I am looking to travel to China for a few supplier visits, and have requested for them to visit their local government office and have them issue me the invitation letter (This is the procedure that the chinese embassy in Sri Lanka said was the way to get the invitation letter). I had asked a few of the suppliers to provide me with the letter, as I will be moving around in china for a few days visiting them respectively at different times. All of them asked me for the basic information only (passport scanned copies, scanned copies of older chinese entry permits, travel plan, etc), however, one of the supplier has asked me for a copy of my local business registration document. Is this really necessary? I feel quite reluctant to give my business license copy in this sort of situation. Would anyone happen to know anything about this, and if it is actually necessary for me to provide them with it?