code: func ValidateLogOpt(cfg map[string]string) error {
  	for key := range cfg {
  		switch key {
  		case splunkURLKey:
  		case splunkTokenKey:
  		case splunkSourceKey:
  		case splunkSourceTypeKey:
  		case splunkIndexKey:
  		case splunkCAPathKey:
  		case splunkCANameKey:
  		case splunkInsecureSkipVerifyKey:
  		case splunkFormatKey:
  		case splunkVerifyConnectionKey:
  		case splunkGzipCompressionKey:
  		case splunkGzipCompressionLevelKey:
  		case envKey:
  		case envRegexKey:
  		case labelsKey:
  		case labelsRegexKey:
  		case tagKey:
  		default:
  			return fmt.Errorf("unknown log opt '%s' for %s log driver", key, driverName)
  		}
  	}
  	return nil
  }
docs: // ValidateLogOpt looks for all supported by splunk driver options