Get a token that can be used to rehydrate the operation.

Calls the service and updates the state of the long-running operation. Properties directly handled by the OperationInternal class, such as RawResponse don't need to be updated. Operation-specific properties, such as "CreateOn" or "LastModified", must be manually updated by the operation implementing this method. Usage example: async ValueTask<OperationState> IOperation.UpdateStateAsync(bool async, CancellationToken cancellationToken) { Response<R> response = async ? <async service call> : <sync service call>; if (<operation succeeded>) return OperationState.Success(response.GetRawResponse(), <parse response>); if (<operation failed>) return OperationState.Failure(response.GetRawResponse()); return OperationState.Pending(response.GetRawResponse()); }