code: @Override
      public GetDownloadUrlForLayerResult getDownloadUrlForLayer(GetDownloadUrlForLayerRequest request) {
          request = beforeClientExecution(request);
          return executeGetDownloadUrlForLayer(request);
      }
docs: <p>
  Retrieves the pre-signed Amazon S3 download URL corresponding to an image layer. You can only get URLs for image
  layers that are referenced in an image.
  </p>
  <note>
  <p>
  This operation is used by the Amazon ECR proxy, and it is not intended for general use by customers for pulling
  and pushing images. In most cases, you should use the <code>docker</code> CLI to pull, tag, and push images.
  </p>
  </note>
  
  @param getDownloadUrlForLayerRequest
  @return Result of the GetDownloadUrlForLayer operation returned by the service.
  @throws ServerException
  These errors are usually caused by a server-side issue.
  @throws InvalidParameterException
  The specified parameter is invalid. Review the available parameters for the API request.
  @throws LayersNotFoundException
  The specified layers could not be found, or the specified layer is not valid for this repository.
  @throws LayerInaccessibleException
  The specified layer is not available because it is not associated with an image. Unassociated image
  layers may be cleaned up at any time.
  @throws RepositoryNotFoundException
  The specified repository could not be found. Check the spelling of the specified repository and ensure
  that you are performing operations on the correct registry.
  @sample AmazonECR.GetDownloadUrlForLayer
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/ecr-2015-09-21/GetDownloadUrlForLayer" target="_top">AWS API
  Documentation</a>