readonly validation = new UmbValidationController(this)
  readonly onCompletionScriptValidator =
    new UmbPropertyDatasetPropertyValidator(this.validation, {
      propertyAlias: 'onCompletionScript',
      check: (value: string | undefined) =>
        !!value && !new RegExp(ON_COMPLETION_SCRIPT_PATTERN).test(value),
      message: () =>
        'The script must start with function onFormCompletion(values) => {',
    })