code: @Override
      public StartUserImportJobResult startUserImportJob(StartUserImportJobRequest request) {
          request = beforeClientExecution(request);
          return executeStartUserImportJob(request);
      }
docs: <p>
  Starts the user import.
  </p>
  
  @param startUserImportJobRequest
  Represents the request to start the user import job.
  @return Result of the StartUserImportJob operation returned by the service.
  @throws ResourceNotFoundException
  This exception is thrown when the Amazon Cognito service cannot find the requested resource.
  @throws InvalidParameterException
  This exception is thrown when the Amazon Cognito service encounters an invalid parameter.
  @throws TooManyRequestsException
  This exception is thrown when the user has made too many requests for a given operation.
  @throws InternalErrorException
  This exception is thrown when Amazon Cognito encounters an internal error.
  @throws PreconditionNotMetException
  This exception is thrown when a precondition is not met.
  @throws NotAuthorizedException
  This exception is thrown when a user is not authorized.
  @sample AWSCognitoIdentityProvider.StartUserImportJob
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/cognito-idp-2016-04-18/StartUserImportJob" target="_top">AWS
  API Documentation</a>