code: @Override
      public CancelSchemaExtensionResult cancelSchemaExtension(CancelSchemaExtensionRequest request) {
          request = beforeClientExecution(request);
          return executeCancelSchemaExtension(request);
      }
docs: <p>
  Cancels an in-progress schema extension to a Microsoft AD directory. Once a schema extension has started
  replicating to all domain controllers, the task can no longer be canceled. A schema extension can be canceled
  during any of the following states; <code>Initializing</code>, <code>CreatingSnapshot</code>, and
  <code>UpdatingSchema</code>.
  </p>
  
  @param cancelSchemaExtensionRequest
  @return Result of the CancelSchemaExtension operation returned by the service.
  @throws EntityDoesNotExistException
  The specified entity could not be found.
  @throws ClientException
  A client exception has occurred.
  @throws ServiceException
  An exception has occurred in AWS Directory Service.
  @sample AWSDirectoryService.CancelSchemaExtension
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/ds-2015-04-16/CancelSchemaExtension" target="_top">AWS API
  Documentation</a>