Function AsyncOperationRequest.cancel

Cancels the request. This will cause isComplete to return true once the cancellation has been processed, but [AsyncOperationResponse.wasSuccessful] will return false (unless it completed before the cancellation was processed, in which case it is still allowed to finish successfully).

After cancelling a request, you should still wait for it to complete to ensure that the task has actually released its resources before doing anything else on it.

Once a cancellation request has been sent, it cannot be undone.