src/Base/ConfigReader.php
protected function normalizeConfigPath($filePath, $basePath = null) {
        if (null === $basePath) {
            $basePath = $this->path;
        }
        $fullPath = strpos($filePath, '/') === 0 ? $filePath : $basePath . DIRECTORY_SEPARATOR . $filePath;
        return $fullPath;
    }
protected function normalizeConfigPath($filePath, $basePath = null) {
        if (null === $basePath) {
            $basePath = $this->path;
        }
        $fullPath = strpos($filePath, '/') === 0 ? $filePath : $basePath . DIRECTORY_SEPARATOR . $filePath;
        return $fullPath;
    }
Normalize config file path
@param string $filePath
@param string|null $basePath
@return string