code: public function validate(ElggEntity $entity) {
  
  		$shortname = $this->getShortname();
  		$validation = new ValidationStatus();
  
  		$value = elgg_extract($shortname, $_FILES, array());
  		$error_type = elgg_extract('error', $value);
  
  		$has_uploaded_file = $error_type != UPLOAD_ERR_NO_FILE;
  		if (!$has_uploaded_file) {
  			if ($this->isRequired() && empty($this->getValues($entity))) {
  				$validation->setFail(elgg_echo('prototyper:validate:error:required', array($this->getLabel())));
  			}
  		} else {
  			$error = hypeApps()->uploader->getFriendlyUploadError($error_type);
  			if ($error) {
  				$validation->setFail($error);
  			} else {
  				$validation = $this->applyValidationRules($value, $validation, $entity);
  			}
  		}
  
  		return $validation;
  	}
docs: {@inheritdoc}