code: func (s *ChangesService) RetrieveCommitMessageFromChangeEdit(changeID string) (string, *Response, error) {
  	u := fmt.Sprintf("changes/%s/edit:message", changeID)
  	return getStringResponseWithoutOptions(s.client, u)
  }
docs: // RetrieveCommitMessageFromChangeEdit retrieves commit message from change edit.
  // The commit message is returned as base64 encoded string.
  //
  // Gerrit API docs: https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#get-edit-message