PHPMD\RuleSetFactory::parseRuleReferenceNode PHP Method

    private function parseRuleReferenceNode(RuleSet $ruleSet, \SimpleXMLElement $ruleNode)
    {
        $ref = (string) $ruleNode['ref'];
        $fileName = substr($ref, 0, strpos($ref, '.xml/') + 4);
        $fileName = $this->createRuleSetFileName($fileName);
        $ruleName = substr($ref, strpos($ref, '.xml/') + 5);
        $ruleSetFactory = new RuleSetFactory();
        $ruleSetRef = $ruleSetFactory->createSingleRuleSet($fileName);
        $rule = $ruleSetRef->getRuleByName($ruleName);
        if (trim($ruleNode['name']) !== '') {
            $rule->setName((string) $ruleNode['name']);
        }
        if (trim($ruleNode['message']) !== '') {
            $rule->setMessage((string) $ruleNode['message']);
        }
        if (trim($ruleNode['externalInfoUrl']) !== '') {
            $rule->setExternalInfoUrl((string) $ruleNode['externalInfoUrl']);
        }
        foreach ($ruleNode->children() as $node) {
            if ($node->getName() === 'description') {
                $rule->setDescription((string) $node);
            } elseif ($node->getName() === 'example') {
                $rule->addExample((string) $node);
            } elseif ($node->getName() === 'priority') {
                $rule->setPriority((int) $node);
            } elseif ($node->getName() === 'properties') {
                $this->parsePropertiesNode($rule, $node);
            }
        }
        if ($rule->getPriority() <= $this->minimumPriority) {
            $ruleSet->addRule($rule);
        }
    }