[MM-29217] Remove Posts.ParentId (#17923)

model/command_webhook.go

@@ -14,7 +14,6 @@ type CommandWebhook struct {
 	UserId    string
 	ChannelId string
 	RootId    string
-	ParentId  string
 	UseCount  int
 }
 
@@ -57,9 +56,5 @@ func (o *CommandWebhook) IsValid() *AppError {
 		return NewAppError("CommandWebhook.IsValid", "model.command_hook.root_id.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	if o.ParentId != "" && !IsValidId(o.ParentId) {
-		return NewAppError("CommandWebhook.IsValid", "model.command_hook.parent_id.app_error", nil, "", http.StatusBadRequest)
-	}
-
 	return nil
 }