code: func expandCustomizationIdentification(d *schema.ResourceData) types.CustomizationIdentification {
  	obj := types.CustomizationIdentification{
  		JoinWorkgroup: d.Get(cWindowsKeyPrefix + "." + "workgroup").(string),
  		JoinDomain:    d.Get(cWindowsKeyPrefix + "." + "join_domain").(string),
  		DomainAdmin:   d.Get(cWindowsKeyPrefix + "." + "domain_admin_user").(string),
  	}
  	if v, ok := d.GetOk(cWindowsKeyPrefix + "." + "domain_admin_password"); ok {
  		obj.DomainAdminPassword = &types.CustomizationPassword{
  			Value:     v.(string),
  			PlainText: true,
  		}
  	}
  	return obj
  }
docs: // expandCustomizationIdentification reads certain ResourceData keys and
  // returns a CustomizationIdentification.