code: @Override
      public ActivatePipelineResult activatePipeline(ActivatePipelineRequest request) {
          request = beforeClientExecution(request);
          return executeActivatePipeline(request);
      }
docs: <p>
  Validates the specified pipeline and starts processing pipeline tasks. If the pipeline does not pass validation,
  activation fails.
  </p>
  <p>
  If you need to pause the pipeline to investigate an issue with a component, such as a data source or script, call
  <a>DeactivatePipeline</a>.
  </p>
  <p>
  To activate a finished pipeline, modify the end date for the pipeline and then activate it.
  </p>
  
  @param activatePipelineRequest
  Contains the parameters for ActivatePipeline.
  @return Result of the ActivatePipeline operation returned by the service.
  @throws PipelineNotFoundException
  The specified pipeline was not found. Verify that you used the correct user and account identifiers.
  @throws PipelineDeletedException
  The specified pipeline has been deleted.
  @throws InternalServiceErrorException
  An internal service error occurred.
  @throws InvalidRequestException
  The request was not valid. Verify that your request was properly formatted, that the signature was
  generated with the correct credentials, and that you haven't exceeded any of the service limits for your
  account.
  @sample DataPipeline.ActivatePipeline
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/datapipeline-2012-10-29/ActivatePipeline" target="_top">AWS
  API Documentation</a>