You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: v289.go
    path of file: ./repos/gitea/models/migrations/v1_22
    
    the code of the file until where you have to start completion: // Copyright 2024 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package v1_
    
func AddDefaultWikiBranch(x *xorm.Engine) error {
	type Repository struct {
		ID                int64
		DefaultWikiBranch string
	}
	if err := x.Sync(&Repository{}); err != nil {
		return err
	}
	_, err := x.Exec("UPDATE `repository` SET default_wiki_branch = 'master' WHERE (default_wiki_branch IS NULL) OR (default_wiki_branch = '')")
	return err
}