Piwik\AssetManager\UIAssetMerger::generateFile PHP Method

    public function generateFile()
    {
        if (!$this->shouldGenerate()) {
            return;
        }
        $this->mergedContent = $this->getMergedAssets();
        $this->postEvent($this->mergedContent);
        $this->adjustPaths();
        $this->addPreamble();
        $this->writeContentToFile();
    }