code: func (s *ChangesService) ChangeCommitMessageInChangeEdit(changeID string, input *ChangeEditMessageInput) (*Response, error) {
  	u := fmt.Sprintf("changes/%s/edit:message", changeID)
  
  	req, err := s.client.NewRequest("PUT", u, input)
  	if err != nil {
  		return nil, err
  	}
  
  	return s.client.Do(req, nil)
  }
docs: // ChangeCommitMessageInChangeEdit modify commit message.
  // The request body needs to include a ChangeEditMessageInput entity.
  //
  // If a change edit doesn’t exist for this change yet, it is created.
  // As response “204 No Content” is returned.
  //
  // Gerrit API docs: https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#put-change-edit-message