find_objects_async
Description:
public async List<Object> find_objects_async (Attributes match, Cancellable? cancellable) throws Error
  
  Find the objects matching the passed attributes.
This call will return immediately and complete asynchronously.
If the match Attributes is floating, it is consumed.
Parameters:
| this | The session to find objects on. | 
| match | The attributes to match. | 
| cancellable | Optional cancellation object or  | 
| callback | Called when the operation completes. | 
| user_data | Data to pass to the callback. |