Queries a calendar for a calendar component object based on its unique identifier.
The call is finished by get_object.end from the callback.
Use get_objects_for_uid to get list of all objects for the given uid, which includes master object and all detached instances.
| uid |
Unique identifier for a calendar component. |
| rid |
Recurrence identifier. |
| cancellable |
a Cancellable; can be null |
| callback |
callback to call when a result is ready |
| user_data |
user data for the |