Transformer/MailerTransformer.php
protected function transformIterable($value)
    {
        $params = array();

        foreach ($value as $key => $val) {
            if (!empty($val)) {
                $params[$key] = $this->transform($val);
            }
        }

        return $params;
    }
protected function transformIterable($value)
    {
        $params = array();

        foreach ($value as $key => $val) {
            if (!empty($val)) {
                $params[$key] = $this->transform($val);
            }
        }

        return $params;
    }
Transform iterable value into array

@param \Traversable|array $value
@return array