code: private Set<String> validateJobImage(final String image) {
      final Set<String> errors = Sets.newHashSet();
  
      if (image == null) {
        errors.add("Image was not specified.");
      } else {
        // Validate image name
        validateImageReference(image, errors);
      }
  
      return errors;
    }
docs: Validate the Job's image by checking it's not null or empty and has the right format.
  
  @param image The image String
  
  @return A set of error Strings