protected function getMergedConfigurationForSitePackage($sitePackageKey)
    {
        if (array_key_exists($sitePackageKey, $this->mergedConfigurationCache)) {
            return $this->mergedConfigurationCache[$sitePackageKey];
        }

        $configuration = $this->configuration;
        $siteConfiguration = Arrays::getValueByPath($configuration, ['packages' , $sitePackageKey]);
        if ($siteConfiguration) {
            $result = Arrays::arrayMergeRecursiveOverrule($configuration, $siteConfiguration);
        } else {
            $result = $configuration;
        }

        $this->mergedConfigurationCache[$sitePackageKey] = $result;
        return $result;
    }