public function getMaximumLevels()
    {
        if ($this->maximumLevels === null) {
            $this->maximumLevels = $this->fusionValue('maximumLevels');
            if ($this->maximumLevels > self::MAXIMUM_LEVELS_LIMIT) {
                $this->maximumLevels = self::MAXIMUM_LEVELS_LIMIT;
            }
        }

        return $this->maximumLevels;
    }