Retry strategy allows retrying a long write operation. There are two supported scenarios:- Once the failure happens you may re-emit the failure you've received, applying your own transformations like a delay or any other,aiming to postpone the retry procedure.- If that Observable calls {@code onComplete} or {@code onError} then {@code retry} will call {@code onCompleted} or {@code onError} on the child subscription. The emission will be forwarded as an operation result.For general documentation related to retrying please refer to http://reactivex.io/documentation/operators/retry.html