WC_Email_Customer_Completed_Order::get_subject PHP Method

        public function get_subject()
        {
            if (!empty($this->object) && $this->object->has_downloadable_item()) {
                return apply_filters('woocommerce_email_subject_customer_completed_order', $this->format_string($this->subject_downloadable), $this->object);
            } else {
                return apply_filters('woocommerce_email_subject_customer_completed_order', $this->format_string($this->subject), $this->object);
            }
        }

 /**
  * get_subject function.
  *
  * @access public
  * @return string
  */
 function get_subject()
 {
     return apply_filters('woocommerce_subscriptions_email_subject_customer_completed_renewal_order', parent::get_subject(), $this->object);
 }