OptionValueToLabel action incorrectly returns an array when single parameter is provided

OptionValueToLabel action incorrectly returns an array when single parameter is provided.

$parameters->getParameter('value'); returns an array when a single parameter is provided and thus the is_array check passes. I cannot see how the elseif statement would ever be reached. The return value is always an array. This then causes the parameter validate function to throw the exception: "requires a single value a multiple value is given".

  protected function doAction(ParameterBagInterface $parameters, ParameterBagInterface $output) {
    $value = $parameters->getParameter('value');
    $option_group_id = $this->configuration->getParameter('option_group_id');
    if (is_array($value)) {
      $labels = array();
      foreach($value as $v) {
        $label = civicrm_api3('OptionValue', 'getvalue', array('return' => 'label', 'value' => $v, 'option_group_id' => $option_group_id));
        $labels[] = $label;
      }
      $output->setParameter('value', $labels);
    } elseif (!empty($value)) {
      $label = civicrm_api3('OptionValue', 'getvalue', array('return' => 'label', 'value' => $value, 'option_group_id' => $option_group_id));
      $output->setParameter('value', $label);
    }
  }

Agileware Ref: CIVICRM-2073