middleware/request_id.go
func GetReqID(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if reqID, ok := ctx.Value(RequestIDKey).(string); ok {
		return reqID
	}
	return ""
}
func GetReqID(ctx context.Context) string {
	if ctx == nil {
		return ""
	}
	if reqID, ok := ctx.Value(RequestIDKey).(string); ok {
		return reqID
	}
	return ""
}
// GetReqID returns a request ID from the given context if one is present.
// Returns the empty string if a request ID cannot be found.