public static function timestampToFlexiDateTime($timpestamp = null)
    {
        $flexiDateTime = null;
        if (!is_null($timpestamp)) {
            $date          = new \DateTime();
            $date->setTimestamp($timpestamp);
            $flexiDateTime = $date->format('Y-m-dTH:i:s');
        }
        return $flexiDateTime;
    }