Neos\Flow\Core\Migrations\AbstractMigration::processConfiguration PHP Method

    protected function processConfiguration($configurationType, \Closure $processor, $saveResult = false)
    {
        if (is_dir($this->targetPackageData['path'] . '/Configuration') === false) {
            return;
        }
        $yamlPathsAndFilenames = Files::readDirectoryRecursively($this->targetPackageData['path'] . '/Configuration', 'yaml', true);
        $configurationPathsAndFilenames = array_filter($yamlPathsAndFilenames, function ($pathAndFileName) use($configurationType) {
            if (strpos(basename($pathAndFileName, '.yaml'), $configurationType) === 0) {
                return true;
            } else {
                return false;
            }
        });
        $yamlSource = new YamlSource();
        foreach ($configurationPathsAndFilenames as $pathAndFilename) {
            $originalConfiguration = $configuration = $yamlSource->load(substr($pathAndFilename, 0, -5));
            $processor($configuration);
            if ($saveResult === true && $configuration !== $originalConfiguration) {
                $yamlSource->save(substr($pathAndFilename, 0, -5), $configuration);
            }
        }
    }