code: public ServiceFuture<Void> cancelDeletionAsync(String thumbprintAlgorithm, String thumbprint, final ServiceCallback<Void> serviceCallback) {
          return ServiceFuture.fromHeaderResponse(cancelDeletionWithServiceResponseAsync(thumbprintAlgorithm, thumbprint), serviceCallback);
      }
docs: Cancels a failed deletion of a certificate from the specified account.
  If you try to delete a certificate that is being used by a pool or compute node, the status of the certificate changes to deleteFailed. If you decide that you want to continue using the certificate, you can use this operation to set the status of the certificate back to active. If you intend to delete the certificate, you do not need to run this operation after the deletion failed. You must make sure that the certificate is not being used by any resources, and then you can try again to delete the certificate.
  
  @param thumbprintAlgorithm The algorithm used to derive the thumbprint parameter. This must be sha1.
  @param thumbprint The thumbprint of the certificate being deleted.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object