If I retrieve all folders via getItemsRequest, and iterate through them to try determine their types (so, for instance, I can cause my program logic to ignore query folders or shared folders), what's the best way to determine the folder type?

The "Folder" class doesn't have a "folder type" indicator. Each of the derived folder types DO have a "folder type" indicator, which doesn't make sense, since I presumably already know the folder type if I had enough foresight to instantiate an object of that type...

Any suggestions on divining the actual folder type from the base class Folder?