Asynchronously requests that the provider populates the completion results for context.
For providers that would like to populate a [[email protected]] while those results are displayed to the user, [ [email protected]_proposals_for_provider] may be used to reduce latency until the user sees results.
| this | |
| context | |
| cancellable |
a Cancellable or null |
| callback |
a callback to execute upon completion |
| user_data |
closure data for |