return state.anchorPosition?.let { anchorPosition ->
  val anchorPage = state.closestPageToPosition(anchorPosition)
  anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
}

`getRefreshKey()` 를 고정값으로 사용하면 `airlineList.refresh()` 를 호출할 때 오류가 발생합니다. https://developer.android.com/topic/libraries/architecture/paging/v3-paged-data?hl=ko#pagingsource 처럼 이렇게 바꿔줘야 합니다. ```kotlin return state.anchorPosition?.let { anchorPosition -> val anchorPage = state.closestPageToPosition(anchorPosition) anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1) } ```