code: func (def *PackageDef) VersionFile() string {
  	// It is already validated by LoadPackageDef, so just return it.
  	for _, chunk := range def.Data {
  		if chunk.VersionFile != "" {
  			return chunk.VersionFile
  		}
  	}
  	return ""
  }
docs: // VersionFile defines where to drop JSON file with package version.