Piwik\AssetManager\UIAssetMerger\StylesheetUIAssetMerger::concatenateAssets PHP Method

    protected function concatenateAssets()
    {
        $mergedContent = '';
        foreach ($this->getAssetCatalog()->getAssets() as $uiAsset) {
            $uiAsset->validateFile();
            try {
                $path = $uiAsset->getAbsoluteLocation();
            } catch (Exception $e) {
                $path = null;
            }
            if (!empty($path) && Common::stringEndsWith($path, '.css')) {
                // to fix #10173
                $mergedContent .= "\n" . $this->getCssStatementForReplacement($path) . "\n";
                $this->cssAssetsToReplace[] = $uiAsset;
            } else {
                $content = $this->processFileContent($uiAsset);
                $mergedContent .= $this->getFileSeparator() . $content;
            }
        }
        $this->mergedContent = $mergedContent;
    }