public function collect(EncodeValueEvent $event)
    {
        $value = $event->getValue();

        if ($value instanceof Definition) {
            foreach ($value->getRequiredLibraries() as $library) {
                if (isset($this->libraries[$library])) {
                    continue;
                }

                if (isset($this->stylesheets[$library])) {
                    foreach ($this->stylesheets[$library] as $asset) {
                        $this->assets->addStylesheet($asset[0], $asset[1]);
                    }
                }

                if (isset($this->javascripts[$library])) {
                    foreach ($this->javascripts[$library] as $asset) {
                        $this->assets->addJavascript($asset[0], $asset[1]);
                    }
                }

                $this->libraries[$library] = true;
            }
        }
    }