code: public Observable<BackupStorageResult> backupStorageAccountAsync(String vaultBaseUrl, String storageAccountName) {
          return backupStorageAccountWithServiceResponseAsync(vaultBaseUrl, storageAccountName).map(new Func1<ServiceResponse<BackupStorageResult>, BackupStorageResult>() {
              @Override
              public BackupStorageResult call(ServiceResponse<BackupStorageResult> response) {
                  return response.body();
              }
          });
      }
docs: Backs up the specified storage account.
  Requests that a backup of the specified storage account be downloaded to the client. This operation requires the storage/backup permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param storageAccountName The name of the storage account.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the BackupStorageResult object