code: public ServiceFuture<BackupCertificateResult> backupCertificateAsync(String vaultBaseUrl, String certificateName, final ServiceCallback<BackupCertificateResult> serviceCallback) {
          return ServiceFuture.fromResponse(backupCertificateWithServiceResponseAsync(vaultBaseUrl, certificateName), serviceCallback);
      }
docs: Backs up the specified certificate.
  Requests that a backup of the specified certificate be downloaded to the client. All versions of the certificate will be downloaded. This operation requires the certificates/backup permission.
  
  @param vaultBaseUrl The vault name, for example https://myvault.vault.azure.net.
  @param certificateName The name of the certificate.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object