Lookup which collection is assigned to this alias.
Aliases help determine well known collections, such as `default`.
If service is null, then [func@Service.get_sync] will be called to get the default [
class@Service] proxy.
This method may block and should not be used in user interface threads.
| service |
a secret service object |
| alias |
the alias to lookup |
| flags |
options for the collection initialization |
| cancellable |
optional cancellation object |
|
the collection, or null if none assigned to the alias |