gistfile1.txt

Optional<Stream<Long>> nextVersions = findAllVersionsAfter(lastFetchedVersion);

    return nextVersions.map(
        optionalVersion ->
            optionalVersion.map(
                version ->
                    new IdBucketDataStore<>(
                        bucketIdHandler.versionToBucketId(version),
                        getStoreForVersion(version)
                    )
            )
    );