func (c *StandardClaims) Valid() error {
	if err := c.StandardClaims.Valid(); err != nil {
		return err
	}

	if c.AccessKey == "" && c.Subject == "" {
		return jwtgo.NewValidationError("accessKey/sub missing",
			jwtgo.ValidationErrorClaimsInvalid)
	}

	return nil
}

// NewMapClaims - Initializes a new map claims
func NewMapClaims() *MapClaims {