protected function getSchemaFileName($folder, $schema)
    {
        $file = null;

        foreach (['yml', 'yaml'] as $ext) {
            $fileCheck = $folder.'/'.$schema.'.'.$ext;
            if (is_readable($fileCheck)) {
                $file = $fileCheck;
                break;
            }
        }

        if (is_null($file)) {
            throw new SchemaParserException(sprintf('Cannot find schema for "%s" in "%s"', $schema, $folder));
        }

        return $file;
    }