if len(form) == 0 {
		return nil
	}

	sessionPolicyStr := form.Get(stsPolicy)
	if len(sessionPolicyStr) == 0 {
		return nil
	}

	sessionPolicy, err := policy.ParseConfig(bytes.NewReader([]byte(sessionPolicyStr)))
	if err != nil {
		return err
	}

	// Version in policy must not be empty
	if sessionPolicy.Version == "" {

	type objectLockConfig Config
	parsedConfig := objectLockConfig{}

	if err := d.DecodeElement(&parsedConfig, &start); err != nil {
		return err
	}

	if parsedConfig.ObjectLockEnabled != Enabled {
		return fmt.Errorf("only 'Enabled' value is allowed to ObjectLockEnabled element")
	}

	*config = Config(parsedConfig)
	return nil
}

// ToRetention - convert to Retention type.